WorldWideScience

Sample records for microwave diode control

  1. Control of GaAs Microwave Schottky Diode Electrical Characteristics by Contact Geometry: The Gap Diode.

    Science.gov (United States)

    1982-05-01

    versus incident RF power of a Gap diode (V- bO ) .. . . . Ii i.... .. l -- _ _ __ll .. . I -82- c"-)) IZDn UU Figure 36. Single-ended mixer conversion...267 (1970). (12] C.J. Madams , D.V. Morgan, J.M. Howes, "Outmigratlon of Gallium from Au-GaAs Interfaces", Electronic Letters, Vol. 11(24), 574 (1975

  2. A Survey on Small Size Diodes For Microwave And Millimeter Wave Frequency Region

    Directory of Open Access Journals (Sweden)

    Rahul Ranjan, Prashant Kumar, Neha Singh

    2014-06-01

    Full Text Available This paper attempts to present a collection of microwave and millimetre wave semiconductor diodes. These semiconductor diodes are operates at microwave frequencies and millimetre frequencies. The invention of these semiconductor diodes led to almost complete replacement of vacuum devices which are bulky and large in size. Because of small size a large number of diodes can integrate on a single chip and this arrangement forms very large-scale integrated circuits which led to solid-state replacement on computer switching circuits. This paper surveys characteristics, applications, advantages and disadvantages of microwave and millimetre wave semiconductor devices.

  3. Magnetic frequency tuning of the microwave Gunn diode oscillator

    OpenAIRE

    Gorbatov, Sergey S.; A.A. Semenov; Usanov, Dmitry A.; Sorokin, A. N.; Kvasko, Vladimir Yu.

    2009-01-01

    It has been found experimentally that the oscillation frequency of a Gunn diode placed in the low-dimensional resonance system “metal pin–closely set short-circuiter” can be effectively controlled by magnetic field applied in the normal direction with respect to the waveguide wide wall.

  4. An Analysis of the Equivalent Resistance of PIN Diodes at Microwave Frequencies

    Institute of Scientific and Technical Information of China (English)

    YANG Guo-yu; SONG Kai-jun; MAO Rui-jie; LU Shi-qiang

    2004-01-01

    The forward bias equivalent resistance of PIN diodes, an important parameter in applications, is usually measured at lower frequencies. But in fact, due to skin effect the effective conduction area of the region I of a PIN diode decreases as the frequency increases. In this paper, the affection of skin effect to forward bias equivalent resistance is considered and an analytic expression of the equivalent resistance of the region I is presented. In result, the forward bias resistance ora PIN diode at microwave frequencies is much higher than that at DC and low frequencies. It is necessary, therefore,to consider the skin effect of PIN diodes in high frequency applications.

  5. Controlled Microwave Heating Accelerates Rolling Circle Amplification.

    Science.gov (United States)

    Yoshimura, Takeo; Suzuki, Takamasa; Mineki, Shigeru; Ohuchi, Shokichi

    2015-01-01

    Rolling circle amplification (RCA) generates single-stranded DNAs or RNA, and the diverse applications of this isothermal technique range from the sensitive detection of nucleic acids to analysis of single nucleotide polymorphisms. Microwave chemistry is widely applied to increase reaction rate as well as product yield and purity. The objectives of the present research were to apply microwave heating to RCA and indicate factors that contribute to the microwave selective heating effect. The microwave reaction temperature was strictly controlled using a microwave applicator optimized for enzymatic-scale reactions. Here, we showed that microwave-assisted RCA reactions catalyzed by either of the four thermostable DNA polymerases were accelerated over 4-folds compared with conventional RCA. Furthermore, the temperatures of the individual buffer components were specifically influenced by microwave heating. We concluded that microwave heating accelerated isothermal RCA of DNA because of the differential heating mechanisms of microwaves on the temperatures of reaction components, although the overall reaction temperatures were the same.

  6. Phase stabilization of nanosecond microwave oscillations in Gunn-diode-based oscillators

    Science.gov (United States)

    Konev, V. Yu.; Klimov, A. I.; Koval'chuk, O. B.; Gubanov, V. P.; Kozhevnikov, V. Yu.; Kozyrev, A. V.

    2015-03-01

    The "intrusion" of the phase of a Gunn-diode nanosecond microwave oscillator by applying a modulating voltage pulse is numerically simulated. The dependences of the microwave oscillation phase on the spread of the pulse rise time and modulating pulse amplitude are revealed. The standard deviation of the phase lag time in a 3-cm-range oscillator relative to a fixed level at the leading edge of the modulating phase is measured. Phase synchronization between two electrodynamically uncoupled oscillators that are simultaneously excited by a single modulator is studied experimentally.

  7. Tunable diode laser control by a stepping Michelson interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Valentin, A.; Nicolas, C.; Henry, L.; Mantz, A.W.

    1987-01-01

    A tunable diode laser beam is sent through a Michelson interferometer and is locked to a fringe of the diode laser interferometer pattern by controlling the diode laser polarization current. The path difference change of the Michelson interferometer is controlled step by step by a stabilized He--Ne red laser. When the interferometer path differences increases or decreases, the polarization current of the diode is forced to change in order to preserve the interference order of the diode beam. At every step the diode frequency is accurately fixed and its phase noise significantly reduced.

  8. Combustion control using an IR diode laser

    Energy Technology Data Exchange (ETDEWEB)

    Niska, J.; Rensgard, A.; Malmberg, D. [MEFOS, Lulea (Sweden)

    2003-07-01

    Tunable diode laser absorption spectroscopy (TDLAS) is a recent development in process instrumentation. This paper describes the testing of a commercial TDLAS instrument for continuous oxygen analysis of the furnace combustion gases in an industrial reheating furnace and in a pilot furnace at MEFOS. A time-averaged oxygen concentration signal with a TDC2000 furnace controller at MEFOS was used to prove automatic control of the air-to-fuel ratio. The local measurements of the oxygen concentration using a zirconia probe in both furnaces compared well with the oxygen concentrations measured by the TDLAS instrument. The advantage of the diode laser is its high reliability for average gas concentration measurements in the path of the beam, when compared to point gas analysis with conventional zirconia instrumentation. Improved process control is derived from reliable gas analysis, which translates into energy savings, reduced emissions and improved productivity for steel reheating furnaces. 7 refs., 8 figs.

  9. Electronically controlled heat sink for high-power laser diodes

    Science.gov (United States)

    Vetrovec, John

    2009-05-01

    We report on a novel electronically controlled active heat sink for high-power laser diodes offering unparalleled capacity in high-heat flux handling and temperature control. The heat sink receives diode waste heat at high flux and transfers it at reduced flux to environment, coolant fluid, heat pipe, or structure. Thermal conductance of the heat sink is electronically adjustable, allowing for precise control of diode temperature and the diode light wavelength. When pumping solid-state or alkaline vapor lasers, diode wavelength can be precisely temperature-tuned to the gain medium absorption features. This paper presents the heat sink physics, engineering design, and performance modeling.

  10. Controlled Microwave Heating Accelerates Rolling Circle Amplification.

    Directory of Open Access Journals (Sweden)

    Takeo Yoshimura

    Full Text Available Rolling circle amplification (RCA generates single-stranded DNAs or RNA, and the diverse applications of this isothermal technique range from the sensitive detection of nucleic acids to analysis of single nucleotide polymorphisms. Microwave chemistry is widely applied to increase reaction rate as well as product yield and purity. The objectives of the present research were to apply microwave heating to RCA and indicate factors that contribute to the microwave selective heating effect. The microwave reaction temperature was strictly controlled using a microwave applicator optimized for enzymatic-scale reactions. Here, we showed that microwave-assisted RCA reactions catalyzed by either of the four thermostable DNA polymerases were accelerated over 4-folds compared with conventional RCA. Furthermore, the temperatures of the individual buffer components were specifically influenced by microwave heating. We concluded that microwave heating accelerated isothermal RCA of DNA because of the differential heating mechanisms of microwaves on the temperatures of reaction components, although the overall reaction temperatures were the same.

  11. Y-branch integrated dual wavelength laser diode for microwave generation by sideband injection locking.

    Science.gov (United States)

    Huang, Jin; Sun, Changzheng; Xiong, Bing; Luo, Yi

    2009-11-01

    A Y-branch integrated dual wavelength laser diode is fabricated for optical microwave generation based on the principle of sideband injection locking. The device integrates a master laser and a slave laser with associated Y-branch coupler. By directly modulating the master laser near its relaxation resonance frequency, multiple sidebands are generated due to enhanced modulation nonlinearity. Beat signal with high spectral purity is obtained by injection locking the slave laser to one of the modulation sidebands. A millimeter-wave carrier of 42-GHz with a phase noise of -94.6 dBc/Hz at 10 kHz offset is demonstrated.

  12. Spectral control of diode lasers using external waveguide circuits

    NARCIS (Netherlands)

    Oldenbeuving, Ruud

    2013-01-01

    We investigated spectral control of diode lasers using external waveguide circuits. The purpose of this work is to investigate such external control for providing a new class of diode lasers with technologically interesting properties, such as a narrow spectral bandwidth and spectrally tunable

  13. Spectral control of diode lasers using external waveguide circuits

    NARCIS (Netherlands)

    Oldenbeuving, R.M.

    2013-01-01

    We investigated spectral control of diode lasers using external waveguide circuits. The purpose of this work is to investigate such external control for providing a new class of diode lasers with technologically interesting properties, such as a narrow spectral bandwidth and spectrally tunable outpu

  14. Digital control of diode laser for atmospheric spectroscopy

    Science.gov (United States)

    Menzies, R. T.; Rutledge, C. W. (Inventor)

    1985-01-01

    A system is described for remote absorption spectroscopy of trace species using a diode laser tunable over a useful spectral region of 50 to 200 cm(-1) by control of diode laser temperature over range from 15 K to 100 K, and tunable over a smaller region of typically 0.1 to 10 cm(-1) by control of the diode laser current over a range from 0 to 2 amps. Diode laser temperature and current set points are transmitted to the instrument in digital form and stored in memory for retrieval under control of a microprocessor during measurements. The laser diode current is determined by a digital to analog converter through a field effect transistor for a high degree of ambient temperature stability, while the laser diode temperature is determined by set points entered into a digital to analog converter under control of the microprocessor. Temperature of the laser diode is sensed by a sensor diode to provide negative feedback to the temperature control circuit that responds to the temperature control digital to analog converter.

  15. High stable power control of a laser diode

    Institute of Scientific and Technical Information of China (English)

    YANG Jiu-ru; LI Cheng; YE Hong-an; L(U) Guo-hui; JIA Shi-lou

    2006-01-01

    In this paper,the low and the high frequency noises of a laser diode have been analyzed. Based on the analysis a novel scheme that adapts analog and digital hybrid techniques is proposed to stabilize the output power of a laser diode. With the hybrid controller,the low and the high frequency noises of a laser diode are conspicuously reduced.By accurate calculation,the short-term stability of the output power of laser diode reaches ±0.55‰, and the long-term stability is ±0.7‰.

  16. Metal-oxide-semiconductor capacitors and Schottky diodes studied with scanning microwave microscopy at 18 GHz

    Energy Technology Data Exchange (ETDEWEB)

    Kasper, M. [Christian Doppler Laboratory for Nanoscale Methods in Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz (Austria); Gramse, G. [Biophysics Institute, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz (Austria); Hoffmann, J. [METAS, National Metrology Institute of Switzerland, Lindenweg 50, 3003 Bern-Wabern (Switzerland); Gaquiere, C. [MC2 technologies, 5 rue du Colibri, 59650 Villeneuve D' ascq (France); Feger, R.; Stelzer, A. [Institute for Communications Engineering and RF-Systems, Johannes Kepler University, Altenberger Str. 69, 4040 Linz (Austria); Smoliner, J. [Vienna University of Technology, Institute for Solid State Electronics, Floragasse 7, 1040 Vienna (Austria); Kienberger, F., E-mail: ferry-kienberger@keysight.com [Keysight Technologies Austria, Measurement Research Lab, Gruberstrasse 40, 4020 Linz (Austria)

    2014-11-14

    We measured the DC and RF impedance characteristics of micrometric metal-oxide-semiconductor (MOS) capacitors and Schottky diodes using scanning microwave microscopy (SMM). The SMM consisting of an atomic force microscopy (AFM) interfaced with a vector network analyser (VNA) was used to measure the reflection S11 coefficient of the metallic MOS and Schottky contact pads at 18 GHz as a function of the tip bias voltage. By controlling the SMM biasing conditions, the AFM tip was used to bias the Schottky contacts between reverse and forward mode. In reverse bias direction, the Schottky contacts showed mostly a change in the imaginary part of the admittance while in forward bias direction the change was mostly in the real part of the admittance. Reference MOS capacitors which are next to the Schottky diodes on the same sample were used to calibrate the SMM S11 data and convert it into capacitance values. Calibrated capacitance between 1–10 fF and 1/C{sup 2} spectroscopy curves were acquired on the different Schottky diodes as a function of the DC bias voltage following a linear behavior. Additionally, measurements were done directly with the AFM-tip in contact with the silicon substrate forming a nanoscale Schottky contact. Similar capacitance-voltage curves were obtained but with smaller values (30–300 aF) due to the corresponding smaller AFM-tip diameter. Calibrated capacitance images of both the MOS and Schottky contacts were acquired with nanoscale resolution at different tip-bias voltages.

  17. On the Long-Term Stability of Microwave Radiometers Using Noise Diodes for Calibration

    Science.gov (United States)

    Brown, Shannon T.; Desai, Shailen; Lu, Wenwen; Tanner, Alan B.

    2007-01-01

    Results are presented from the long-term monitoring and calibration of the National Aeronautics and Space Administration Jason Microwave Radiometer (JMR) on the Jason-1 ocean altimetry satellite and the ground-based Advanced Water Vapor Radiometers (AWVRs) developed for the Cassini Gravity Wave Experiment. Both radiometers retrieve the wet tropospheric path delay (PD) of the atmosphere and use internal noise diodes (NDs) for gain calibration. The JMR is the first radiometer to be flown in space that uses NDs for calibration. External calibration techniques are used to derive a time series of ND brightness for both instruments that is greater than four years. For the JMR, an optimal estimator is used to find the set of calibration coefficients that minimize the root-mean-square difference between the JMR brightness temperatures and the on-Earth hot and cold references. For the AWVR, continuous tip curves are used to derive the ND brightness. For the JMR and AWVR, both of which contain three redundant NDs per channel, it was observed that some NDs were very stable, whereas others experienced jumps and drifts in their effective brightness. Over the four-year time period, the ND stability ranged from 0.2% to 3% among the diodes for both instruments. The presented recalibration methodology demonstrates that long-term calibration stability can be achieved with frequent recalibration of the diodes using external calibration techniques. The JMR PD drift compared to ground truth over the four years since the launch was reduced from 3.9 to - 0.01 mm/year with the recalibrated ND time series. The JMR brightness temperature calibration stability is estimated to be 0.25 K over ten days.

  18. Polarization control based interference microwave photonic filters

    Science.gov (United States)

    Madziar, Krzysztof; Galwas, Bogdan

    2016-12-01

    In this paper we present a concept of multi-line Microwave Photonic Filter (MPF) based on polarization beam splitting and polarization control in each line. Coefficients of investigated filter are determined by attenuation of its lines and that on the other hand can be manipulated by change of the polarization in the fiber. Presented results involve scattering parameters (S21) measurements of optical path over polarization control unit rotation, scattering parameters (S21) characteristics of investigated filter and transmission optimization capabilities.

  19. Microwave assisted transformation of N,N-diphenylamine as precursors of organic light emitting diodes (OLED)

    Energy Technology Data Exchange (ETDEWEB)

    Jefri,; Wahyuningrum, Deana, E-mail: deana@chem.itb.ac.id [Organic Chemistry Research Division, Department of Chemistry, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesha 10, Bandung 40132 (Indonesia)

    2015-09-30

    In this research, study on the transformation of N,N-diphenylamine (DPA) using iodine (I2) utilizing solid state Microwave Assisted Organic Synthesis (MAOS) method has been carried out. The reaction was performed by variations of three parameters namely the mole of reagents, the amount and type of solid support (alumina/Al2O3), and the reaction conditions. Experimental results showed that neutral-alumina was a better solid support than basic-alumina. The optimum temperature for the reaction was approximately at 125-133 °C with reaction time of 15 minutes and microwave reactor power at 500-600 W. The separation of the yellowish green product solution with preparative Thin Layer Chromatography (TLC) method using n-hexane:ethyl acetate = 4:1 (v/v) as eluent yielded two fractions (I and II) and both fractions can undergo fluorescence under 365 nm UV light. Based on the LC chromatogram with methanol:water = 95:5 (v/v) as eluent and its corresponding mass spectra (ESI+), fraction I contained three compounds, which were tetracarbazole A, triphenylamine, and impurities in the form of plasticizer such as bis(2-ethylhexyl) phthalate. Fraction II also contained three compounds, which were tetracarbazole C, tetraphenylhydrazine, and plasticizer such as bis(2-ethylhexyl) phthalate. Both FT-IR (KBr disks) and NMR (500 MHz, CDCl{sub 3}) spectra of fraction I and II confirmed the aromatic amine groups in those compounds. The observed fluorescence colors of fraction I and II were violet and violet-blue, respectively. Based on their structures and fluorescence characters, the compounds in fraction I and II have the potential to be used as Organic Light Emitting Diode (OLED) compound precursors.

  20. Microwave assisted transformation of N,N-diphenylamine as precursors of organic light emitting diodes (OLED)

    Science.gov (United States)

    Jefri, Wahyuningrum, Deana

    2015-09-01

    In this research, study on the transformation of N,N-diphenylamine (DPA) using iodine (I2) utilizing solid state Microwave Assisted Organic Synthesis (MAOS) method has been carried out. The reaction was performed by variations of three parameters namely the mole of reagents, the amount and type of solid support (alumina/Al2O3), and the reaction conditions. Experimental results showed that neutral-alumina was a better solid support than basic-alumina. The optimum temperature for the reaction was approximately at 125-133 °C with reaction time of 15 minutes and microwave reactor power at 500-600 W. The separation of the yellowish green product solution with preparative Thin Layer Chromatography (TLC) method using n-hexane:ethyl acetate = 4:1 (v/v) as eluent yielded two fractions (I and II) and both fractions can undergo fluorescence under 365 nm UV light. Based on the LC chromatogram with methanol:water = 95:5 (v/v) as eluent and its corresponding mass spectra (ESI+), fraction I contained three compounds, which were tetracarbazole A, triphenylamine, and impurities in the form of plasticizer such as bis(2-ethylhexyl) phthalate. Fraction II also contained three compounds, which were tetracarbazole C, tetraphenylhydrazine, and plasticizer such as bis(2-ethylhexyl) phthalate. Both FT-IR (KBr disks) and NMR (500 MHz, CDCl3) spectra of fraction I and II confirmed the aromatic amine groups in those compounds. The observed fluorescence colors of fraction I and II were violet and violet-blue, respectively. Based on their structures and fluorescence characters, the compounds in fraction I and II have the potential to be used as Organic Light Emitting Diode (OLED) compound precursors.

  1. Josephson junction microwave modulators for qubit control

    Science.gov (United States)

    Naaman, O.; Strong, J. A.; Ferguson, D. G.; Egan, J.; Bailey, N.; Hinkey, R. T.

    2017-02-01

    We demonstrate Josephson junction based double-balanced mixer and phase shifter circuits operating at 6-10 GHz and integrate these components to implement both a monolithic amplitude/phase vector modulator and an I/Q quadrature mixer. The devices are actuated by flux signals, dissipate no power on chip, exhibit input saturation powers in excess of 1 nW, and provide cryogenic microwave modulation solutions for integrated control of superconducting qubits.

  2. High brightness diode lasers controlled by volume Bragg gratings

    Science.gov (United States)

    Glebov, Leonid

    2017-02-01

    Volume Bragg gratings (VBGs) recorded in photo-thermo-refractive (PTR) glass are holographic optical elements that are effective spectral and angular filters withstanding high power laser radiation. Reflecting VBGs are narrow-band spectral filters while transmitting VBGs are narrow-band angular filters. The use of these optical elements in external resonators of semiconductor lasers enables extremely resonant feedback that provides dramatic spectral and angular narrowing of laser diodes radiation without significant power and efficiency penalty. Spectral narrowing of laser diodes by reflecting VBGs demonstrated in wide spectral region from near UV to 3 μm. Commercially available VBGs have spectral width ranged from few nanometers to few tens of picometers. Efficient spectral locking was demonstrated for edge emitters (single diodes, bars, modules, and stacks), vertical cavity surface emitting lasers (VCSELs), grating coupled surface emitting lasers (GCSELs), and interband cascade lasers (ICLs). The use of multiplexed VBGs provides multiwavelength emission from a single emitter. Spectrally locked semiconductor lasers demonstrated CW power from milliwatts to a kilowatt. Angular narrowing by transmitting VBGs enables single transverse mode emission from wide aperture diode lasers having resonators with great Fresnel numbers. This feature provides close to diffraction limit divergence along a slow axis of wide stripe edge emitters. Radiation exchange between lasers by means of spatially profiled or multiplexed VBGs enables coherent combining of diode lasers. Sequence of VBGs or multiplexed VBGs enable spectral combining of spectrally narrowed diode lasers or laser modules. Thus the use of VBGs for diode lasers beam control provides dramatic increase of brightness.

  3. Light-controlled microwave whispering-gallery-mode quasi-optical resonators at 50W LED array illumination

    Directory of Open Access Journals (Sweden)

    V. B. Yurchenko

    2015-08-01

    Full Text Available We present experimental observations of light-controlled resonance effects in microwave whispering-gallery-mode quasi-optical dielectric-semiconductor disk resonators in the frequency band of 5 GHz to 20 GHz arising due to illumination from a light emitting diode (LED of 50W power range. We obtain huge enhancement of photo-sensitivity (growing with the resonator Q-factor that makes light-microwave interaction observable with an ordinary light (no laser at conventional brightness (like an office lighting in quasi-optical microwave structures at rather long (centimeter-scale wavelength. We also demonstrate non-conventional photo-response of Fano resonances when the light suppresses one group of resonances and enhances another group. The effects could be used for the optical control and quasi-optical switching of microwave propagation through either one or another frequency channel.

  4. Contactless Microwave Measurements of Photoconductivity in Silicon Hyperdoped with Chalcogens

    Science.gov (United States)

    2012-01-01

    microwaves emitted by a Millitech Gunn diode pass, via a waveguide, through an isolator to protect the source from reflections. A ‘‘magic tee’’ then...sample. Lasers were modulated at 286Hz using a Thorlabs LDC500 laser diode controller. The photoinduced change in the intensity of reflected microwaves was

  5. Magnetoelectrical control of nonreciprocal microwave response in a multiferroic helimagnet

    Science.gov (United States)

    Iguchi, Y.; Nii, Y.; Onose, Y.

    2017-05-01

    The control of physical properties by external fields is essential in many contemporary technologies. For example, conductance can be controlled by a gate electric field in a field effect transistor, which is a main component of integrated circuits. Optical phenomena induced by an electric field such as electroluminescence and electrochromism are useful for display and other technologies. Control of microwave propagation is also important for future wireless communication technology. Microwave properties in solids are dominated mostly by magnetic excitations, which cannot be easily controlled by an electric field. One solution to this problem is to use magnetically induced ferroelectrics (multiferroics). Here we show that microwave nonreciprocity, that is, different refractive indices for microwaves propagating in opposite directions, could be reversed by an external electric field in a multiferroic helimagnet Ba2Mg2Fe12O22. This approach offers an avenue for the electrical control of microwave properties.

  6. A user oriented computer program for the analysis of microwave mixers, and a study of the effects of the series inductance and diode capacitance on the performance of some simple mixers

    Science.gov (United States)

    Siegel, P. H.; Kerr, A. R.

    1979-01-01

    A user oriented computer program for analyzing microwave and millimeter wave mixers with a single Schottky barrier diode of known I-V and C-V characteristics is described. The program first performs a nonlinear analysis to determine the diode conductance and capacitance waveforms produced by the local oscillator. A small signal linear analysis is then used to find the conversion loss, port impedances, and input noise temperature of the mixer. Thermal noise from the series resistance of the diode and shot noise from the periodically pumped current in the diode conductance are considered. The effects of the series inductance and diode capacitance on the performance of some simple mixer circuits using a conventional Schottky diode, a Schottky diode in which there is no capacitance variation, and a Mott diode are studied. It is shown that the parametric effects of the voltage dependent capacitance of a conventional Schottky diode may be either detrimental or beneficial depending on the diode and circuit parameters.

  7. Amplitude to phase conversion of InGaAs pin photo-diodes for femtosecond lasers microwave signal generation

    CERN Document Server

    Zhang, W; Lours, M; Seidelin, S; Santarelli, G; Coq, Y Le

    2011-01-01

    When a photo-diode is illuminated by a pulse train from a femtosecond laser, it generates microwaves components at the harmonics of the repetition rate within its bandwidth. The phase of these components (relative to the optical pulse train) is known to be dependent on the optical energy per pulse. We present an experimental study of this dependence in InGaAs pin photo-diodes illuminated with ultra-short pulses generated by an Erbium-doped fiber based femtosecond laser. The energy to phase dependence is measured over a large range of impinging pulse energies near and above saturation for two typical detectors, commonly used in optical frequency metrology with femtosecond laser based optical frequency combs. When scanning the optical pulse energy, the coefficient which relates phase variations to energy variations is found to alternate between positive and negative values, with many (for high harmonics of the repetition rate) vanishing points. By operating the system near one of these vanishing points, the typ...

  8. Microwave quantum logic spectroscopy and control of molecular ions

    DEFF Research Database (Denmark)

    Shi, M.; F. Herskind, P.; Drewsen, M.;

    2013-01-01

    A general method for rotational microwave spectroscopy and control of polar molecular ions via direct microwave addressing is considered. Our method makes use of spatially varying AC Stark shifts, induced by far off-resonant, focused laser beams to achieve an effective coupling between the rotati......A general method for rotational microwave spectroscopy and control of polar molecular ions via direct microwave addressing is considered. Our method makes use of spatially varying AC Stark shifts, induced by far off-resonant, focused laser beams to achieve an effective coupling between...... the rotational state of a molecular ion and the electronic state of an atomic ion. In this setting, the atomic ion is used for read-out of the molecular ion state, in a manner analogous to quantum logic spectroscopy based on Raman transitions. In addition to high-precision spectroscopy, this setting allows...

  9. Microwave quantum logic spectroscopy and control of molecular ions

    DEFF Research Database (Denmark)

    Shi, M.; F. Herskind, P.; Drewsen, M.

    2013-01-01

    A general method for rotational microwave spectroscopy and control of polar molecular ions via direct microwave addressing is considered. Our method makes use of spatially varying AC Stark shifts, induced by far off-resonant, focused laser beams to achieve an effective coupling between the rotati......A general method for rotational microwave spectroscopy and control of polar molecular ions via direct microwave addressing is considered. Our method makes use of spatially varying AC Stark shifts, induced by far off-resonant, focused laser beams to achieve an effective coupling between...... for rotational ground state cooling, and can be considered as a candidate for the quantum information processing with polar molecular ions. All elements of our proposal can be realized with currently available technology....

  10. Analytical scanning evanescent microwave microscope and control stage

    Science.gov (United States)

    Xiang, Xiao-Dong; Gao, Chen; Duewer, Fred; Yang, Hai Tao; Lu, Yalin

    2009-06-23

    A scanning evanescent microwave microscope (SEMM) that uses near-field evanescent electromagnetic waves to probe sample properties is disclosed. The SEMM is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The SEMM has the ability to map dielectric constant, loss tangent, conductivity, electrical impedance, and other electrical parameters of materials. Such properties are then used to provide distance control over a wide range, from to microns to nanometers, over dielectric and conductive samples for a scanned evanescent microwave probe, which enable quantitative non-contact and submicron spatial resolution topographic and electrical impedance profiling of dielectric, nonlinear dielectric and conductive materials. The invention also allows quantitative estimation of microwave impedance using signals obtained by the scanned evanescent microwave probe and quasistatic approximation modeling. The SEMM can be used to measure electrical properties of both dielectric and electrically conducting materials.

  11. Investigations of 2.9-GHz Resonant Microwave-Sensitive Ag/MgO/Ge/Ag Tunneling Diodes

    Science.gov (United States)

    Qasrawi, A. F.; Khanfar, H. K.

    2013-12-01

    In this work, a resonant microwave-sensitive tunneling diode has been designed and investigated. The device, which is composed of a magnesium oxide (MgO) layer on an amorphous germanium (Ge) thin film, was characterized by means of temperature-dependent current ( I)-voltage ( V), room-temperature differential resistance ( R)-voltage, and capacitance ( C)-voltage characteristics. The device resonating signal was also tested and evaluated at 2.9 GHz. The I- V curves reflected weak temperature dependence and a wide tunneling region with peak-to-valley current ratio of ˜1.1. The negative differential resistance region shifts toward lower biasing voltages as temperature increases. The true operational limit of the device was determined as 350 K. A novel response of the measured R- V and C- V to the incident alternating-current (ac) signal was observed at 300 K. Particularly, the response to a 100-MHz signal power ranging from the standard Bluetooth limit to the maximum output power of third-generation mobile phones reflects a wide range of tunability with discrete switching property at particular power limits. In addition, when the tunnel device was implanted as an amplifier for a 2.90-GHz resonating signal of the power of wireless local-area network (LAN) levels, signal gain of 80% with signal quality factor of 4.6 × 104 was registered. These remarkable properties make devices based on MgO-Ge interfaces suitable as electronic circuit elements for microwave applications, bias- and time-dependent electronic switches, and central processing unit (CPU) clocks.

  12. Control of powerful microwaves using EBG plasma structures

    Science.gov (United States)

    Simonchik, Leanid; Callegari, Thierry; Sokoloff, Jerome; Usachonak, Maxim

    2016-09-01

    Glow discharge plasmas have great potential for application as control elements in microwave devices designed on the basis of electromagnetic band gap (EBG) structures. In this report, a plasma control of powerful microwave propagation by means of 1D and 2D EBG structures is under investigation. Three pulsed discharges in argon (or helium) at atmospheric pressure are applied in the capacity of plasma inhomogeneities. Temporal behavior of electron concentration in discharge is determined. The transmission spectra of 1D EBG structure formed solely by plasma in the X-waveguide are measured. The amplitudes of short ( 200 ns) and powerful (50 kW) microwave pulses at frequency of 9.15 GHz are strongly suppressed (more than on 40 dB) when plasma structure exists. The propagation of these powerful microwave pulses through the triangular metallic 2D EBG structure with the plasma control elements is investigated, too. It is shown that the transmission of the 2D EBG structure at the angle of 45o ceases quickly (during a few tenth of nanoseconds) when plasma acts as a compensator of defect in the front row of the structure. On the contrary, the transmission arises quickly once plasma acts as an additional defect. The support of BRFBR-CNRS grant F15F-004 is acknowledged.

  13. Diode laser sensor for process control and environmental monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Zaatar, Y.; Bechara, J.; Khoury, A.; Zaouk, D. [Lebanese Univ., Physics Dept., Fanar (Lebanon); Charles, J.-P. [Metz Univ., L.I.C.M., Metz, 57 (France)

    2000-04-01

    Absorption spectroscopy with tunable diode lasers (TDLAS) in the infrared region is a well-known technique for the chemical analysis of gas mixtures. The laser provides a high selectivity, which is important in industrial environments such as in-line stack monitoring, where complex gas mixtures are present. A wavelength tunable diode laser in the near infrared region has been utilised as a light source in absorption measurements of air pollution resulting from energy usage for industry. The emission frequency can be varied over a relatively wide spectral range by changing the current and temperature of the diode. (Author)

  14. Artificial color perception using microwaves

    CERN Document Server

    Choudhury, Debesh

    2013-01-01

    We report the feasibility of artificial color perception under microwave illumination using a standard microwave source and an antenna. We have sensed transmitted microwave power through color objects and have distinguished the colors by analyzing the sensed transmitted power. Experiments are carried out using a Gunn diode as the microwave source, some colored liquids as the objects and a microwave diode as the detector. Results are presented which open up an unusual but new way of perceiving colors using microwaves.

  15. Artificial Intelligent Control for a Novel Advanced Microwave Biodiesel Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Wali, W A; Hassan, K H; Cullen, J D; Al-Shamma' a, A I; Shaw, A; Wylie, S R, E-mail: w.wali@2009.ljmu.ac.uk [Built Environment and Sustainable Technologies Institute (BEST), School of the Built Environment, Faculty of Technology and Environment Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom)

    2011-08-17

    Biodiesel, an alternative diesel fuel made from a renewable source, is produced by the transesterification of vegetable oil or fat with methanol or ethanol. In order to control and monitor the progress of this chemical reaction with complex and highly nonlinear dynamics, the controller must be able to overcome the challenges due to the difficulty in obtaining a mathematical model, as there are many uncertain factors and disturbances during the actual operation of biodiesel reactors. Classical controllers show significant difficulties when trying to control the system automatically. In this paper we propose a comparison of artificial intelligent controllers, Fuzzy logic and Adaptive Neuro-Fuzzy Inference System(ANFIS) for real time control of a novel advanced biodiesel microwave reactor for biodiesel production from waste cooking oil. Fuzzy logic can incorporate expert human judgment to define the system variables and their relationships which cannot be defined by mathematical relationships. The Neuro-fuzzy system consists of components of a fuzzy system except that computations at each stage are performed by a layer of hidden neurons and the neural network's learning capability is provided to enhance the system knowledge. The controllers are used to automatically and continuously adjust the applied power supplied to the microwave reactor under different perturbations. A Labview based software tool will be presented that is used for measurement and control of the full system, with real time monitoring.

  16. Artificial Intelligent Control for a Novel Advanced Microwave Biodiesel Reactor

    Science.gov (United States)

    Wali, W. A.; Hassan, K. H.; Cullen, J. D.; Al-Shamma'a, A. I.; Shaw, A.; Wylie, S. R.

    2011-08-01

    Biodiesel, an alternative diesel fuel made from a renewable source, is produced by the transesterification of vegetable oil or fat with methanol or ethanol. In order to control and monitor the progress of this chemical reaction with complex and highly nonlinear dynamics, the controller must be able to overcome the challenges due to the difficulty in obtaining a mathematical model, as there are many uncertain factors and disturbances during the actual operation of biodiesel reactors. Classical controllers show significant difficulties when trying to control the system automatically. In this paper we propose a comparison of artificial intelligent controllers, Fuzzy logic and Adaptive Neuro-Fuzzy Inference System(ANFIS) for real time control of a novel advanced biodiesel microwave reactor for biodiesel production from waste cooking oil. Fuzzy logic can incorporate expert human judgment to define the system variables and their relationships which cannot be defined by mathematical relationships. The Neuro-fuzzy system consists of components of a fuzzy system except that computations at each stage are performed by a layer of hidden neurons and the neural network's learning capability is provided to enhance the system knowledge. The controllers are used to automatically and continuously adjust the applied power supplied to the microwave reactor under different perturbations. A Labview based software tool will be presented that is used for measurement and control of the full system, with real time monitoring.

  17. Actively controlled tuning of an external cavity diode laser by polarization spectroscopy.

    Science.gov (United States)

    Führer, Thorsten; Stang, Denise; Walther, Thomas

    2009-03-30

    We report on an universal method to achieve and sustain a large mode-hop free tuning range of an external cavity diode laser. By locking one of the resonators using a closed loop control based on polarization spectroscopy while tuning the laser we achieved mode-hop free tuning of up to 130 GHz with a non AR-coated, off-the-shelf laser diode.

  18. Real-time power measurement and control for high power diode laser

    Science.gov (United States)

    Qin, Wen-bin; Liu, You-qiang; Cao, Yin-hua; Wang, Zhi-yong

    2011-06-01

    As the continual improvement of technology and beam quality, diode laser, with poor beam quality, no longer just apply to pump solid-state laser. As a kind of implement of laser materials processing, high-power diode laser has been used in manufacture, as a brand new means of laser processing. Due to the influence of inevitable unstable factors, for example, the temperature of water-cooler, the current of power supply, etc, the output power of diode laser will be unstable. And laser output power, as an important parameter, frequently affects the performance of the laser beam and the experimental results of processing, especially in the laser materials processing. Therefore, researching the real-time power measurement and control of high power diode laser has great significance, and for diode laser, it would improve performance of itself. To achieve the purpose of real-time detection, traditional measuring method, placing a power sensor behind the total-reflection mirror of laser resonant cavity, is mainly applied in the system of gas laser and solid-state laser. However, Owing to the high integration level of diode laser, traditional measuring method can't be adopted. A technique for real-time measure output power of high power diode laser is developed to improve quality of the laser in this paper. A lens placed at an angle of 45° in the system was used to sample output light of laser, and a piece of ground glass was used to uniform the beam power density, then the photoelectric detector received an optic signal and converted it into electric signal. This feeble signal was processed by amplification circuit with a filter. Finally, this detected electric signal was applied to accomplish the closed-loop control of power. The performance of power measurement and control system was tested with the 300W diode laser, and the measuring inaccuracy achieved was less than +/-1%.

  19. Thermoelectric temperature control system for the pushbroom microwave radiometer (PBMR)

    Science.gov (United States)

    Dillon-Townes, L. A.; Averill, R. D.

    1984-06-01

    A closed loop thermoelectric temperature control system is developed for stabilizing sensitive RF integrated circuits within a microwave radiometer to an accuracy of + or - 0.1 C over a range of ambient conditions from -20 C to +45 C. The dual mode (heating and cooling) control concept utilizes partial thermal isolation of the RF units from an instrument deck which is thermally controlled by thermoelectric coolers and thin film heaters. The temperature control concept is simulated with a thermal analyzer program (MITAS) which consists of 37 nodes and 61 conductors. A full scale thermal mockup is tested in the laboratory at temperatures of 0 C, 21 C, and 45 C to confirm the validity of the control concept. A flight radiometer and temperature control system is successfully flight tested on the NASA Skyvan aircraft.

  20. Artificial color perception using microwaves

    OpenAIRE

    Choudhury, Debesh; Caulfield, H. John

    2013-01-01

    We report the feasibility of artificial color perception under microwave illumination using a standard microwave source and an antenna. We have sensed transmitted microwave power through color objects and have distinguished the colors by analyzing the sensed transmitted power. Experiments are carried out using a Gunn diode as the microwave source, some colored liquids as the objects and a microwave diode as the detector. Results are presented which open up an unusual but new way of perceiving...

  1. Analysis and control of the thermal runaway of ceramic slab under microwave heating

    Institute of Scientific and Technical Information of China (English)

    LIU ChangJun; Dongwoo SHEEN

    2008-01-01

    Thermal runaway is a special macroscopic phenomenon of the dielectrics during microwave heating, in which there is a big jump of the steady state temperature while the applied microwave power varies slightly. It hinders the applications of microwave heating technique in industry. A simulation based on the finite differ-ence time domain (FDTD) method to solve Maxwell's equations coupled with the finite difference (FD) method to solve a heat transfer equation (HTE) is presented, and the temperature variation in a ceramic slab during microwave heating is ob-tained. The temperature variation in the ceramic slab during microwave heating is simulated with various ceramic parameters and applied microwave powers so as to analyze the condition under which thermal runaway is introduced. Moreover, a mi-crowave power control method, based on a single temperature threshold and dual applied microwave powers, is presented, which improves microwave heating effi-ciency and controls thermal runaway. The relation between the final applied mi-crowave power and the monitored temperature threshold is presented as well. This method can be applied in many fields related with microwave heating techniques.

  2. Analysis and control of the thermal runaway of ceramic slab under microwave heating

    Institute of Scientific and Technical Information of China (English)

    Dongwoo; SHEEN

    2008-01-01

    Thermal runaway is a special macroscopic phenomenon of the dielectrics during microwave heating,in which there is a big jump of the steady state temperature while the applied microwave power varies slightly.It hinders the applications of microwave heating technique in industry.A simulation based on the finite difference time domain(FDTD) method to solve Maxwell’s equations coupled with the finite difference(FD) method to solve a heat transfer equation(HTE) is presented,and the temperature variation in a ceramic slab during microwave heating is obtained.The temperature variation in the ceramic slab during microwave heating is simulated with various ceramic parameters and applied microwave powers so as to analyze the condition under which thermal runaway is introduced.Moreover,a microwave power control method,based on a single temperature threshold and dual applied microwave powers,is presented,which improves microwave heating efficiency and controls thermal runaway.The relation between the final applied microwave power and the monitored temperature threshold is presented as well.This method can be applied in many fields related with microwave heating techniques.

  3. Practical microwave electron devices

    CERN Document Server

    Meurant, Gerard

    2013-01-01

    Practical Microwave Electron Devices provides an understanding of microwave electron devices and their applications. All areas of microwave electron devices are covered. These include microwave solid-state devices, including popular microwave transistors and both passive and active diodes; quantum electron devices; thermionic devices (including relativistic thermionic devices); and ferrimagnetic electron devices. The design of each of these devices is discussed as well as their applications, including oscillation, amplification, switching, modulation, demodulation, and parametric interactions.

  4. A simple readout electronics for automatic power controlled self-mixing laser diode systems.

    Science.gov (United States)

    Cattini, Stefano; Rovati, Luigi

    2008-08-01

    The paper describes a simple electronic circuit to drive a laser diode for self-mixing interferometry. The network integrates a stable commercial automatic power controller and a current mirror based readout of the interferometric signal. The first prototype version of the circuit has been realized and characterized. The system allows easily performing precise interferometric measurements with no thermostatic circuitry to stabilize the laser diode temperature and an automatic control gain network to compensate emitted optical power fluctuations. To achieve this result, in the paper a specific calibration procedure to be performed is described.

  5. Ultra-low phase-noise microwave generation using a diode-pumped solid-state laser based frequency comb and a polarization-maintaining pulse interleaver

    CERN Document Server

    Portuondo-Campa, Erwin; Kundermann, Stefan; Balet, Laurent; Lecomte, Steve

    2015-01-01

    We report ultra-low phase-noise microwave generation at a 9.6 GHz carrier frequency from optical frequency combs based on diode-pumped solid-state lasers emitting at telecom wavelength and referenced to a common cavity-stabilized continuous-wave laser. Using a novel fibered polarization-maintaining pulse interleaver, a single-oscillator phase-noise floor of -171 dBc/Hz has been measured with commercial PIN InGaAs photodiodes, constituting a record for this type of detector. Also, a direct optical measurement of the stabilized frequency combs timing jitter was performed using a balanced optical cross correlator, allowing for an identification of the origin of the current phase-noise limitations in the system.

  6. Optically tunable microwave, millimeter-wave and submillimeter-wave utilizing single-mode Fabry-Pérot laser diode subject to optical feedback.

    Science.gov (United States)

    Wu, Jian-Wei; Nakarmi, Bikash; Won, Yong Hyub

    2016-02-01

    In this paper, we use optical feedback injection technique to generate tunable microwave, millimeter-wave and submillimeter-wave signals using single-mode Fabry-Pérot laser diode. The beat frequency of the proposed generator ranges from 30.4 GHz to 3.40 THz. The peak power ratio between two resonating modes at the output spectrum of can be less than 0.5 dB by judiciously selecting feedback wavelength. In the stabilization test, the peak fluctuation of photonic signal is as low as 0.19 dB within half hour. Aside from locking regions, where the laser is easily locked by the injection beam, the side-mode suppression ratio is well over 25 dB with the maximum value of 36.6 dB at 30.4 GHz beat frequency. In addition, the minimum beat frequency interval between two adjacent photonic signals is as low as 10 GHz.

  7. Ultra-low phase-noise microwave generation using a diode-pumped solid-state laser based frequency comb and a polarization-maintaining pulse interleaver.

    Science.gov (United States)

    Portuondo-Campa, Erwin; Buchs, Gilles; Kundermann, Stefan; Balet, Laurent; Lecomte, Steve

    2015-12-14

    We report ultra-low phase-noise microwave generation at a 9.6 GHz carrier frequency from optical frequency combs based on diode-pumped solid-state lasers emitting at telecom wavelength and referenced to a common cavity-stabilized continuous-wave laser. Using a novel fibered polarization-maintaining pulse interleaver, a single-oscillator phase-noise floor of -171 dBc/Hz at 10 MHz offset frequency has been measured with commercial PIN InGaAs photodiodes, constituting a record for this type of detector. Also, a direct optical measurement of the stabilized frequency combs' timing jitter was performed using a balanced optical cross correlator, allowing for an identification of the origin of the phase-noise limitations in the system.

  8. FPGA-BASED CONTROL OF THERMOELECTRIC COOLERS FOR LASER DIODE TEMPERATURE REGULATION

    Directory of Open Access Journals (Sweden)

    AHTESHAM ALI

    2012-04-01

    Full Text Available The proportional-integral-derivative (PID controller is the most used controller in the industry. Field programmable gate arrays (FPGAs allow efficient implementation of PID controllers. This paper presents the temperature regulation of a 48W laser diode through thermoelectric coolers (TECs. The temperature regulation system is designed and tested. The results demonstrate the feasibility and applicability of PID control through FPGA.

  9. Controlling microwave signals by means of slow and fast light effects in SOA-EA structures

    DEFF Research Database (Denmark)

    Sales, Salvador; Öhman, Filip; Capmany, José

    2007-01-01

    We present a novel scheme for the control of microwave signals in the optical domain. We propose the use of alternating amplifying and absorbing sections to implement phase control by using fast and slow light effects in semiconductors. The potential benefits from the proposed semiconductor optic...... microwave photonic filters....

  10. Color sensing under microwaves

    Science.gov (United States)

    Choudhury, Debesh

    2013-09-01

    Inspired by recent results of artificial color due to Caulfield, we carry out intuitive experimental investigations on color sensing under microwave illumination. Experiemnts have been carried out using a Gunn diode as the microwave source and a microwave diode as a detector. More precise experimental studies have also been carried out utilizing a vector network analyzer. Preliminary results of the experiments validate the feasibility of sensing and discriminating otherwise visual colors under microwave illumination. Caulfield's presumption possibly paves the way for artificial color perception using microwaves.

  11. Characterization of a Digital Microwave Radiometry System for Noninvasive Thermometry using Temperature Controlled Homogeneous Test Load

    OpenAIRE

    2008-01-01

    Microwave radiometry has been proposed as a viable noninvasive thermometry approach for monitoring subsurface tissue temperatures and potentially controlling power levels of multielement heat applicators during clinical hyperthermia treatments. With the evolution of technology, several analog microwave radiometry devices have been developed for biomedical applications. In this paper, we describe a digital microwave radiometer with built-in electronics for signal processing and automatic self-...

  12. Quasi-Optical Control of Intense Microwave Transmission

    CERN Document Server

    Hirshfield, Jay L

    2005-01-01

    This volume assembles the texts of presentations given at the NATO-sponsored Advanced Research Workshop on Quasi-Optical Transmission of High-Power Microwaves, held in Nizhny Novgorod, Russia in February 2004. The presentations bridge a wide range of technical areas, but share common tools of analysis and design. Applications of quasi-optics extend to the use of high-power microwaves—including millimeter-waves— for radar and communications (especially deep space millimeter-wave systems, space debris detection radar, and radar for the detection of small targets moving over heavy clutter); particle accelerators (especially for a future high-acceleration-gradient electron-positron collider); plasma research (especially for controlled nuclear fusion and waste decontamination); and material processing (in particular, ceramic sintering with millimeter-waves, and the coating of metal surfaces with protective dielectric films.). Scientists and engineers working in any of these areas should benefit significantly f...

  13. Coaxial foilless diode

    Directory of Open Access Journals (Sweden)

    Long Kong

    2014-05-01

    Full Text Available A kind of coaxial foilless diode is proposed in this paper, with the structure model and operating principle of the diode are given. The current-voltage relation of the coaxial foilless diode and the effects of structure parameters on the relation are studied by simulation. By solving the electron motion equation, the beam deviation characteristic in the presence of external magnetic field in transmission process is analyzed, and the relationship between transverse misalignment with diode parameters is obtained. These results should be of interest to the area of generation and propagation of radial beam for application of generating high power microwaves.

  14. Post biopsy Liver Hemorrhage Successfully Controlled by Ultrasound-guided Percutaneous Microwave Ablation

    Directory of Open Access Journals (Sweden)

    Ophelia Ka Heng Wai

    2016-01-01

    Full Text Available Percutaneous microwave coagulation therapy has been one of the major new developments in tumor ablation. Microwave ablation has also been used intraoperatively to achieve hemostasis at surgical margins in laparotomy. However, the use of microwave ablation for coagulation and hemostasis through percutaneous approach has not been described in the literature. Here, we report a case of hepatic amyloidosis with massive post biopsy liver hemorrhage, which could not be by transarterial embolization, and subsequently controlled by ultrasound-guided percutaneous microwave ablation. To the best of our knowledge, this is the first reported case of this technology application in human.

  15. Integrated Microwave Photonic Isolators: Theory, Experimental Realization and Application in a Unidirectional Ring Mode-Locked Laser Diode

    Directory of Open Access Journals (Sweden)

    Martijn J.R. Heck

    2015-09-01

    Full Text Available A novel integrated microwave photonic isolator is presented. It is based on the timed drive of a pair of optical modulators, which transmit a pulsed or oscillating optical signal with low loss, when driven in phase. A signal in the reverse propagation direction will find the modulators out of phase and, hence, will experience high loss. Optical and microwave isolation ratios were simulated to be in the range up to 10 dB and 20 dB, respectively, using parameters representative for the indium phosphide platform. The experimental realization of this device in the hybrid silicon platform showed microwave isolation in the 9 dB–22 dB range. Furthermore, we present a design study on the use of these isolators inside a ring mode-locked laser cavity. Simulations show that unidirectional operation can be achieved, with a 30–50-dB suppression of the counter propagating mode, at limited driving voltages. The potentially low noise and feedback-insensitive operation of such a laser makes it a very promising candidate for use as on-chip microwave or comb generators.

  16. Aerodynamic control in compressible flow using microwave driven discharges

    Science.gov (United States)

    McAndrew, Brendan

    A new aerodynamic control scheme based on heating of the free stream flow is developed. The design, construction, and operation of a unique small scale wind tunnel to perform experiments involving this control scheme is detailed. Free stream heating is achieved by means of microwave driven discharges, and the resulting flow perturbations are used to alter the pressure distribution around a model in the flow. The experimental facility is also designed to allow the injection of an electron beam into the free stream for control of the discharge. Appropriate models for the fluid flow and discharge physics are developed, and comparisons of calculations based on those models are made with experimental results. The calculations have also been used to explore trends in parameters beyond the range possible in the experiments. The results of this work have been (1) the development of an operating facility capable of supporting free stream heat addition experiments in supersonic flow, (2) the development of a compatible instrumented model designed to make lift and drag measurements in a low pressure, high electrical noise environment, (3) a theoretical model to predict the change in breakdown threshold in the presence of an electron beam or other source of ionization, and (4) successful demonstration of aerodynamic control using free stream heat addition.

  17. Devises of automatic for controling of microwave stove for food products’ incinerating

    Directory of Open Access Journals (Sweden)

    M. O. Gren

    2008-05-01

    Full Text Available Development of automatic meant for controlling of microwave oven with the possibility of work on the base of few magnetrons and controlling temperature at the same time with VSWR are represented.

  18. Bright infrared quantum-dot light-emitting diodes through inter-dot spacing control

    KAUST Repository

    Sun, Liangfeng

    2012-05-06

    Infrared light-emitting diodes are currently fabricated from direct-gap semiconductors using epitaxy, which makes them expensive and difficult to integrate with other materials. Light-emitting diodes based on colloidal semiconductor quantum dots, on the other hand, can be solution-processed at low cost, and can be directly integrated with silicon. However, so far, exciton dissociation and recombination have not been well controlled in these devices, and this has limited their performance. Here, by tuning the distance between adjacent PbS quantum dots, we fabricate thin-film quantum-dot light-emitting diodes that operate at infrared wavelengths with radiances (6.4 W sr \\'1 m \\'2) eight times higher and external quantum efficiencies (2.0%) two times higher than the highest values previously reported. The distance between adjacent dots is tuned over a range of 1.3 nm by varying the lengths of the linker molecules from three to eight CH 2 groups, which allows us to achieve the optimum balance between charge injection and radiative exciton recombination. The electroluminescent powers of the best devices are comparable to those produced by commercial InGaAsP light-emitting diodes. By varying the size of the quantum dots, we can tune the emission wavelengths between 800 and 1,850 nm.© 2012 Macmillan Publishers Limited.

  19. Control of Switching Characteristics of Silicon-based Semiconductor Diode Using High Energy Linear Accelerator

    Directory of Open Access Journals (Sweden)

    N. Harihara Krishnan

    2013-05-01

    Full Text Available This paper reports control of switching characteristics of silicon-based semiconductor diode using electron beam produced using linear accelerator. Conventionally, p-n junction chips of diode are exposed to gamma rays from a radioactive source or electron beam from a microtron, depending upon the required level of correction. High energy linear accelerators featuring simultaneous exposure of multiple chips are recent advancements in radiation technology. The paper presents the results of the radiation process using a 10 MeV linear accelerator as applied in industrial manufacturing of a high voltage diode (2600 V. The achieved values of reverse recovery time were found to be within the design limits. The suitability of the new process was verified by constructing the trade-off curve between the switching and conduction parameters of the diode for the complete range using large number of experimental samples. The paper summarizes the advantages of the new process over the conventional methods specifically with reference to industrial requirements. The developed process has been successfully implemented in semiconductor manufacturing.

  20. Bright infrared quantum-dot light-emitting diodes through inter-dot spacing control.

    Science.gov (United States)

    Sun, Liangfeng; Choi, Joshua J; Stachnik, David; Bartnik, Adam C; Hyun, Byung-Ryool; Malliaras, George G; Hanrath, Tobias; Wise, Frank W

    2012-05-06

    Infrared light-emitting diodes are currently fabricated from direct-gap semiconductors using epitaxy, which makes them expensive and difficult to integrate with other materials. Light-emitting diodes based on colloidal semiconductor quantum dots, on the other hand, can be solution-processed at low cost, and can be directly integrated with silicon. However, so far, exciton dissociation and recombination have not been well controlled in these devices, and this has limited their performance. Here, by tuning the distance between adjacent PbS quantum dots, we fabricate thin-film quantum-dot light-emitting diodes that operate at infrared wavelengths with radiances (6.4 W sr(-1) m(-2)) eight times higher and external quantum efficiencies (2.0%) two times higher than the highest values previously reported. The distance between adjacent dots is tuned over a range of 1.3 nm by varying the lengths of the linker molecules from three to eight CH(2) groups, which allows us to achieve the optimum balance between charge injection and radiative exciton recombination. The electroluminescent powers of the best devices are comparable to those produced by commercial InGaAsP light-emitting diodes. By varying the size of the quantum dots, we can tune the emission wavelengths between 800 and 1,850 nm.

  1. Study of an H{sub 2}/CH{sub 4} moderate pressure microwave plasma used for diamond deposition: modelling and IR tuneable diode laser diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Lombardi, G [Laboratoire d' Ingenierie des Materiaux et des Hautes Pressions, CNRS UPR 1311, Universite Paris 13, 99 av. J.B. Clement, 93430 Villetaneuse (France); Hassouni, K [Laboratoire d' Ingenierie des Materiaux et des Hautes Pressions, CNRS UPR 1311, Universite Paris 13, 99 av. J.B. Clement, 93430 Villetaneuse (France); Stancu, G D [INP-Greifswald, Friedrich-Ludwig-Jahn-Str. 19, 17489 Greifswald (Germany); Mechold, L [Laser Components GmbH, Werner-von-Siemens-Str. 15, 82140 Olching (Germany); Roepcke, J [INP-Greifswald, Friedrich-Ludwig-Jahn-Str. 19, 17489 Greifswald (Germany); Gicquel, A [Laboratoire d' Ingenierie des Materiaux et des Hautes Pressions, CNRS UPR 1311, Universite Paris 13, 99 av. J.B. Clement, 93430 Villetaneuse (France)

    2005-08-01

    Infra-red tuneable diode laser spectroscopy (IR TDLAS) has been used to detect and quantify the methyl radical and three stable carbon-containing species (CH{sub 4}, C{sub 2}H{sub 2} and C{sub 2}H{sub 6}) in a moderate pressure microwave (f = 2.45 GHz) bell-jar reactor used for diamond films deposition. A wide range of experimental conditions was investigated, with typical pressure/power required to perform diamond deposition, i.e. pressure from 2500 to 12 000 Pa and power from 600 W to 2 kW, which means gas temperatures ranging from 2200 to 3200 K, when the power density increases from 9 to 30 W cm{sup -3}. Since TDLAS is a line of sight averaged technique, the analysis of the experimental data required the use of a one-dimensional non-equilibrium transport model that provides species density and gas temperature variations along the optical beam. This model describes the plasma in terms of 28 species/131 reactions reactive flow. The thermal non-equilibrium is described by distinguishing a first energy mode for the electron and a second one for the heavy species. Parametric studies as a function of power density and methane percentage in the gas mixture are presented. The good agreement obtained between measurement and one-dimensional radial calculations allows a validation of the thermo-chemical model, which can be used as a tool to enlighten the chemistry in the spatially non-uniform H{sub 2}/CH{sub 4} microwave discharge used for diamond deposition. This is especially of interest for high power density discharge conditions that remain poorly understood.

  2. A gate controlled conjugated single molecule diode: Its rectification could be reversed

    Science.gov (United States)

    Zhang, Qun

    2014-10-01

    A gate controlled Au/diphenyldipyrimidinyl/Au single molecule diode is simulated by a tight-binding Hamiltonian combined with Green's Function and transport methods. After calculating a number of electronic transport characteristics under various gate voltages, a clear modulation by gate is got and when the positive voltage is high enough, the rectification could be reversed. This is advisable for the designing and building future molecular logic devices and integrated circuits.

  3. Molecularly controlled interfacial layer strategy toward highly efficient simple-structured organic light-emitting diodes.

    Science.gov (United States)

    Han, Tae-Hee; Choi, Mi-Ri; Woo, Seong-Hoon; Min, Sung-Yong; Lee, Chang-Lyoul; Lee, Tae-Woo

    2012-03-15

    A highly efficient simplified organic light-emitting diode (OLED) with a molecularly controlled strategy to form near-perfect interfacial layer on top of the anode is demonstrated. A self-organized polymeric hole injection layer (HIL) is exploited increasing hole injection, electron blocking, and reducing exciton quenching near the electrode or conducting polymers; this HIL allows simplified OLED comprised a single small-molecule fluorescent layer to exhibits a high current efficiency (∼20 cd/A).

  4. Optically controlled microwave devices and circuits: Emerging applications in space communications systems

    Science.gov (United States)

    Bhasin, Kul B.; Simons, Rainee N.

    1987-01-01

    Optical control of microwave devices and circuits by an optical fiber has the potential to simplify signal distribution networks in high frequency communications systems. The optical response of two terminal and three terminal (GaAs MESFET, HEMT, PBT) microwave devices are compared and several schemes for controlling such devices by modulated optical signals examined. Monolithic integration of optical and microwave functions on a single semiconductor substrate is considered to provide low power, low loss, and reliable digital and analog optical links for signal distribution.

  5. Silicon Carbide Schottky Barrier Diode

    Science.gov (United States)

    Zhao, Jian H.; Sheng, Kuang; Lebron-Velilla, Ramon C.

    2004-01-01

    This chapter reviews the status of SiC Schottky barrier diode development. The fundamental of Schottky barrier diodes is first provided, followed by the review of high-voltage SiC Schottky barrier diodes, junction-barrier Schottky diodes, and merged-pin-Schottky diodes. The development history is reviewed ad the key performance parameters are discussed. Applications of SiC SBDs in power electronic circuits as well as other areas such as gas sensors, microwave and UV detections are also presented, followed by discussion of remaining challenges.

  6. Single-molecule diodes with high rectification ratios through environmental control.

    Science.gov (United States)

    Capozzi, Brian; Xia, Jianlong; Adak, Olgun; Dell, Emma J; Liu, Zhen-Fei; Taylor, Jeffrey C; Neaton, Jeffrey B; Campos, Luis M; Venkataraman, Latha

    2015-06-01

    Molecular electronics aims to miniaturize electronic devices by using subnanometre-scale active components. A single-molecule diode, a circuit element that directs current flow, was first proposed more than 40 years ago and consisted of an asymmetric molecule comprising a donor-bridge-acceptor architecture to mimic a semiconductor p-n junction. Several single-molecule diodes have since been realized in junctions featuring asymmetric molecular backbones, molecule-electrode linkers or electrode materials. Despite these advances, molecular diodes have had limited potential for applications due to their low conductance, low rectification ratios, extreme sensitivity to the junction structure and high operating voltages. Here, we demonstrate a powerful approach to induce current rectification in symmetric single-molecule junctions using two electrodes of the same metal, but breaking symmetry by exposing considerably different electrode areas to an ionic solution. This allows us to control the junction's electrostatic environment in an asymmetric fashion by simply changing the bias polarity. With this method, we reliably and reproducibly achieve rectification ratios in excess of 200 at voltages as low as 370 mV using a symmetric oligomer of thiophene-1,1-dioxide. By taking advantage of the changes in the junction environment induced by the presence of an ionic solution, this method provides a general route for tuning nonlinear nanoscale device phenomena, which could potentially be applied in systems beyond single-molecule junctions.

  7. Efficient distributed control of light-emitting diode array lighting systems.

    Science.gov (United States)

    Dong, Jianfei; Pandharipande, Ashish

    2012-07-15

    We consider illumination rendering with distributed control of a lighting system with an array of light-emitting diodes (LEDs). As low-cost microprocessors become standard components in LED drivers, distributing the computation of the control signals to individual LED drivers becomes attractive. Common distributed control algorithms require each individual controller to exchange information with all the others and process it. This incurs too large a communication and processing overhead for a low-cost local controller. In this Letter, we propose a distributed control algorithm for achieving global illumination rendering, wherein a controller only needs to communicate within a selected neighborhood. We present design criteria for defining the communication neighborhood and study its impact on rendering performance.

  8. High-fidelity spatial addressing of Ca-43 qubits using near-field microwave control

    CERN Document Server

    Craik, D P L Aude; Sepiol, M A; Harty, T P; Ballance, C J; Stacey, D N; Steane, A M; Lucas, D M; Allcock, D T C

    2016-01-01

    Individual addressing of qubits is essential for scalable quantum computation. Spatial addressing allows unlimited numbers of qubits to share the same frequency, whilst enabling arbitrary parallel operations. We demonstrate addressing of long-lived $^{43}\\text{Ca}^+$ "atomic clock" qubits held in separate zones of a microfabricated surface trap with integrated microwave electrodes. By coherently cancelling the microwave field in one zone we measure a ratio of Rabi frequencies between addressed and non-addressed qubits of up to 1400, implying an addressing error of $1.3\\times 10^{-6}$. Off-resonant excitation prevents this error level being directly demonstrated, but we also show polarization control of the microwave field with error $2\\times 10^{-5}$, sufficient to suppress off-resonant excitation out of the qubit states to the $\\sim 10^{-9}$ level. Such polarization control could enable fast microwave operations.

  9. System for Control,Data Collection and Processing in 8 mm Portable Microwave Radiometer—Scatterometer

    Institute of Scientific and Technical Information of China (English)

    李毅; 方振和; 等

    2002-01-01

    In this paper we describe a system used to control,collect and process data in 8mm portable microwave radiometer-scatterometer,We focus on hardware and software design of the system based on a PIC16F874 chip.The system has been successfully used in an 8mm portable microwave radiometer-scatterometer,compared with other similar systems,the system modularization miniatureization and intelligentization are improved so as to meet portable instrument requirements.

  10. Voltage-controlled spin selection in a magnetic resonant tunneling diode.

    Science.gov (United States)

    Slobodskyy, A; Gould, C; Slobodskyy, T; Becker, C R; Schmidt, G; Molenkamp, L W

    2003-06-20

    We have fabricated all II-VI semiconductor resonant tunneling diodes based on the (Zn,Mn,Be)Se material system, containing dilute magnetic material in the quantum well, and studied their current-voltage characteristics. When subjected to an external magnetic field the resulting spin splitting of the levels in the quantum well leads to a splitting of the transmission resonance into two separate peaks. This is interpreted as evidence of tunneling transport through spin polarized levels, and could be the first step towards a voltage controlled spin filter.

  11. Phase-locked laser diode interferometer: high-speed feedback control system.

    Science.gov (United States)

    Suzuki, T; Sasaki, O; Higuchi, K; Maruyama, T

    1991-09-01

    We have previously proposed a phase-locked laser diode interferometer. In that previous interferometer, however, there was substantial room for improvement in the reduction of measurement time. This reduction is achieved by using a different process for generation of the feedback signal in which the output of a chargecoupled device image sensor is used effectively. We analyze the feedback control system of the interferometer as a discrete-time system and discuss the characteristics of the interferometer. It is shown that the measurement time is much shorter than that of the interferometer proposed previously.

  12. Voltage-Controlled Square/Triangular Wave Generator with Current Conveyors and Switching Diodes

    Directory of Open Access Journals (Sweden)

    Martin Janecek

    2012-12-01

    Full Text Available A novel relaxation oscillator based on integrating the diode-switched currents and Schmitt trigger is presented. It is derived from a known circuit with operational amplifiers where these active elements were replaced by current conveyors. The circuit employs only grounded resistances and capacitance and is suitable for high frequency square and triangular signal generation. Its frequency can be linearly and accurately controlled by voltage that is applied to a high-impedance input. Computer simulation with a model of a manufactured conveyor prototype verifies theoretic assumptions.

  13. Control of plasma profile in microwave discharges via inverse-problem approach

    Directory of Open Access Journals (Sweden)

    Yasuyoshi Yasaka

    2013-12-01

    Full Text Available In the manufacturing process of semiconductors, plasma processing is an essential technology, and the plasma used in the process is required to be of high density, low temperature, large diameter, and high uniformity. This research focuses on the microwave-excited plasma that meets these needs, and the research target is a spatial profile control. Two novel techniques are introduced to control the uniformity; one is a segmented slot antenna that can change radial distribution of the radiated field during operation, and the other is a hyper simulator that can predict microwave power distribution necessary for a desired radial density profile. The control system including these techniques provides a method of controlling radial profiles of the microwave plasma via inverse-problem approach, and is investigated numerically and experimentally.

  14. Advances in microwaves

    CERN Document Server

    Young, Leo

    1967-01-01

    Advances in Microwaves, Volume 2 focuses on the developments in microwave solid-state devices and circuits. This volume contains six chapters that also describe the design and applications of diplexers and multiplexers. The first chapter deals with the parameters of the tunnel diode, oscillators, amplifiers and frequency converter, followed by a simple physical description and the basic operating principles of the solid state devices currently capable of generating coherent microwave power, including transistors, harmonic generators, and tunnel, avalanche transit time, and diodes. The next ch

  15. A 155 Mbps laser diode driver with automatic power and extinction ratio control

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An integrated laser diode driver (LDD) driving an edge-emitting laser diode was designed and fabricated by 0.35 μm BiCMOS technology. This paper proposes a scheme which combines the automatic power control loop and temperature compensation for modulation current in order to maintain constant extinction ratio and average optical power. To implement temperature compensation for modulation current, a novel circuit which generates a PTAT current by using the injecting base current of a bipolar transistor in saturation region, and alternates the amplifier feedback loop (closed or not) to control the state of the current path is presented. Simulation results showed that programmed by choice of external resistors, the IC can provide modulation current from 5 mA to 85 mA with temperature compensation adjustments and independent bias current from 4 mA to 100 mA. Optical test results showed that clear eye-diagrams can be obtained at 155 Mbps, with the output optical power being nearly constant, and the variation of extinction ratio being lower than 0.7 dB.

  16. Multi-resistive reduced graphene oxide diode with reversible surface electrochemical reaction induced carrier control.

    Science.gov (United States)

    Seo, Hyungtak; Ahn, Seungbae; Kim, Jinseo; Lee, Young-Ahn; Chung, Koo-Hyun; Jeon, Ki-Joon

    2014-07-10

    The extended application of graphene-based electronic devices requires a bandgap opening in order to realize the targeted device functionality. Since the bandgap tuning of pristine graphene is limited to 360 meV, the chemical modification of graphene is considered essential to achieve a large bandgap opening at the expense of electrical properties degradation. Reduced graphene oxide (RGO) has attracted significant interest for fabricating graphene-based semiconductors since it has several advantages over other forms of chemically modified graphene; such as tunable bandgap opening, decent electrical properties, and easy synthesis. Because of the reduced bonding nature of RGO, the role of metastable oxygen in the RGO matrix is recently highlighted and it may offer emerging ionic devices. In this study, we show that multi-resistivity RGO/n-Si diodes can be obtained by controlling the RGO thickness at a nanometer scale. This is made possible by (1) a metastable lattice-oxygen drift within bulk RGO and (2) electrochemical ambient hydroxyl (OH) formation at the RGO surface. The effect demonstrated in a p-RGO/n-Si heterojunction diode is equivalent to electrochemically driven reversible electronic manipulation and therefore provides an important basis for the application of O bistability in RGO for chemical sensors and electrocatalysis.

  17. Experimental and numerical evaluations on palm microwave heating for Red Palm Weevil pest control

    Science.gov (United States)

    Massa, Rita; Panariello, Gaetano; Pinchera, Daniele; Schettino, Fulvio; Caprio, Emilio; Griffo, Raffaele; Migliore, Marco Donald

    2017-01-01

    The invasive Red Palm Weevil is the major pest of palms. Several control methods have been applied, however concern is raised regarding the treatments that can cause significant environmental pollution. In this context the use of microwaves is particularly attractive. Microwave heating applications are increasingly proposed in the management of a wide range of agricultural and wood pests, exploiting the thermal death induced in the insects that have a thermal tolerance lower than that of the host matrices. This paper describes research aiming to combat the Red Palm pest using microwave heating systems. An electromagnetic-thermal model was developed to better control the temperature profile inside the palm tissues. In this process both electromagnetic and thermal parameters are involved, the latter being particularly critical depending on plant physiology. Their evaluation was carried out by fitting experimental data and the thermal model with few free parameters. The results obtained by the simplified model well match with both that of a commercial software 3D model and measurements on treated Phoenix canariensis palms with a ring microwave applicator. This work confirms that microwave heating is a promising, eco-compatible solution to fight the spread of weevil. PMID:28361964

  18. Experimental and numerical evaluations on palm microwave heating for Red Palm Weevil pest control

    Science.gov (United States)

    Massa, Rita; Panariello, Gaetano; Pinchera, Daniele; Schettino, Fulvio; Caprio, Emilio; Griffo, Raffaele; Migliore, Marco Donald

    2017-03-01

    The invasive Red Palm Weevil is the major pest of palms. Several control methods have been applied, however concern is raised regarding the treatments that can cause significant environmental pollution. In this context the use of microwaves is particularly attractive. Microwave heating applications are increasingly proposed in the management of a wide range of agricultural and wood pests, exploiting the thermal death induced in the insects that have a thermal tolerance lower than that of the host matrices. This paper describes research aiming to combat the Red Palm pest using microwave heating systems. An electromagnetic-thermal model was developed to better control the temperature profile inside the palm tissues. In this process both electromagnetic and thermal parameters are involved, the latter being particularly critical depending on plant physiology. Their evaluation was carried out by fitting experimental data and the thermal model with few free parameters. The results obtained by the simplified model well match with both that of a commercial software 3D model and measurements on treated Phoenix canariensis palms with a ring microwave applicator. This work confirms that microwave heating is a promising, eco-compatible solution to fight the spread of weevil.

  19. Structure-dependent behaviors of diode-triggered silicon controlled rectifier under electrostatic discharge stress

    Science.gov (United States)

    Zhang, Li-Zhong; Wang, Yuan; He, Yan-Dong

    2016-12-01

    The comprehensive understanding of the structure-dependent electrostatic discharge behaviors in a conventional diode-triggered silicon controlled rectifier (DTSCR) is presented in this paper. Combined with the device simulation, a mathematical model is built to get a more in-depth insight into this phenomenon. The theoretical studies are verified by the transmission-line-pulsing (TLP) test results of the modified DTSCR structure, which is realized in a 65-nm complementary metal-oxide-semiconductor (CMOS) process. The detailed analysis of the physical mechanism is used to provide predictions as the DTSCR-based protection scheme is required. In addition, a method is also presented to achieve the tradeoff between the leakage and trigger voltage in DTSCR. Project supported by the Beijing Municipal Natural Science Foundation, China (Grant No. 4162030) and the National Science and Technology Major Project of China (Grant No. 2013ZX02303002).

  20. Fast Microwave-Induced Thermoacoustic Tomography Based on Multi-Element Phase-Controlled Focus Technique

    Institute of Scientific and Technical Information of China (English)

    ZENG Lü-Ming; XING Da; GU Huai-Min; YANG Di-Wu; YANG Si-Hua; XIANG Liang-Zhong

    2006-01-01

    @@ We develop a fast microwave-induced thermoacoustic tomography system based on a 320-element phase-controlled focus linear transducer array. A 1.2-GHz microwave generator transmits microwave with a pulse width of 0.5 μs and an incident energy density of 0.45 m J/cm2, and the microwave energy is delivered by a rectangular waveguide with a cross section of (80.01 ± 0.02) × 10-4 m2. Compared to single transducer collection, the system with the multi-element linear transducer array can eliminate the mechanical rotation of the transducer, hence can effectively reduce the image blurring and improve the image resolution. Using a phase-controlled focus technique to collect thermoacoustic signals, the data need not be averaged because of a high signal-to-noise ratio, resulting in a total data acquisition time of less than 5s. The system thus provides a rapid and reliable approach to thermoacoustic imaging, which can potentially be developed as a powerful diagnostic tool for early-stage breast caners.

  1. Geometrical control of ionic current rectification in a configurable nanofluidic diode.

    Science.gov (United States)

    Alibakhshi, Mohammad Amin; Liu, Binqi; Xu, Zhiping; Duan, Chuanhua

    2016-09-01

    Control of ionic current in a nanofluidic system and development of the elements analogous to electrical circuits have been the subject of theoretical and experimental investigations over the past decade. Here, we theoretically and experimentally explore a new technique for rectification of ionic current using asymmetric 2D nanochannels. These nanochannels have a rectangular cross section and a stepped structure consisting of a shallow and a deep side. Control of height and length of each side enables us to obtain optimum rectification at each ionic strength. A 1D model based on the Poisson-Nernst-Planck equation is derived and validated against the full 2D numerical solution, and a nondimensional concentration is presented as a function of nanochannel dimensions, surface charge, and the electrolyte concentration that summarizes the rectification behavior of such geometries. The rectification factor reaches a maximum at certain electrolyte concentration predicted by this nondimensional number and decays away from it. This method of fabrication and control of a nanofluidic diode does not require modification of the surface charge and facilitates the integration with lab-on-a-chip fluidic circuits. Experimental results obtained from the stepped nanochannels are in good agreement with the 1D theoretical model.

  2. A Closed-Loop Smart Control System Driving RGB Light Emitting Diodes

    KAUST Repository

    Al-Saggaf, Abeer

    2015-05-01

    The demand for control systems that are highly capable of driving solid-state optoelectronic devices has significantly increased with the advancement of their efficiency and elevation of their current consumption. This work presents a closed-loop control system that is based on a microcontroller embedded system capable of driving high power optoelectronic devices. In this version of the system, the device in the center of control is a high-power red, green, and blue light emitting diode package. The system features a graphical user interface, namely an Android mobile phone application, in which the user can easily use to vary the light color and intensity of the light-emitting device wirelessly via Bluetooth. Included in the system is a feedback mechanism constituted by a red, green, and blue color sensor through which the user can use to observe feedback color information about the emitted light. The system has many commercial application including in-door lighting and research application including plant agriculture research fields.

  3. Enhanced Stability and Controllability of an Ionic Diode Based on Funnel-Shaped Nanochannels with an Extended Critical Region.

    Science.gov (United States)

    Xiao, Kai; Xie, Ganhua; Zhang, Zhen; Kong, Xiang-Yu; Liu, Qian; Li, Pei; Wen, Liping; Jiang, Lei

    2016-05-01

    The enhanced stability and controllability of an ionic diode system based on funnel-shaped nanochannels with a much longer critical region is reported. The polarity of ion transport switching from anion/cation-selective to ambipolar can be controlled by tuning the length and charge of the critical region. This nanofluidic structure anticipates potential applications in single-molecule biosensing, water resource monitoring, and healthcare.

  4. Flow Diode and Method for Controlling Fluid Flow Origin of the Invention

    Science.gov (United States)

    Dyson, Rodger W (Inventor)

    2015-01-01

    A flow diode configured to permit fluid flow in a first direction while preventing fluid flow in a second direction opposite the first direction is disclosed. The flow diode prevents fluid flow without use of mechanical closures or moving parts. The flow diode utilizes a bypass flowline whereby all fluid flow in the second direction moves into the bypass flowline having a plurality of tortuous portions providing high fluidic resistance. The portions decrease in diameter such that debris in the fluid is trapped. As fluid only travels in one direction through the portions, the debris remains trapped in the portions.

  5. Control of a large vacuum wave precursor on the SABRE voltage adder MITL and extraction ion diode

    Science.gov (United States)

    Cuneo, M. E.; Hanson, D. L.; Poukey, J. W.; Menge, P. R.; Savage, M. E.; Smith, J. R.; Bernard, M. A.

    SABRE is a ten-cavity magnetically insulated voltage adder (6MV, 300 kA) used to study ion beam production in high voltage extraction applied-B ion diodes. Observations indicate that the machine power initially propagates in a large-amplitude vacuum wave prior to electron emission. This vacuum wave 'precursor' has an important impact on the turn-on and impedance history of ion diodes. Some typical precursor characteristics are shown using transmission line, diode, and beam current and voltage data and are compared to TWOQUICK simulations. Two techniques are under investigation to control the precursor and its effects on diode performance. A plasma opening switch (POS) has been used to erode the precursor. Field enhancing inserts are also planned to decrease the macroscopic field required for electron emission from the cathode. This will limit the distance over which vacuum and insulated waves separate by propagation at different velocities. Experimental data from the POS technique and TWOQUICK simulations of the insert technique are presented and discussed.

  6. Controllable cross-Kerr interaction between microwave photons in circuit quantum electrodynamics

    Institute of Scientific and Technical Information of China (English)

    Wu Qin-Qin; Liao Jie-Qiao; Kuang Le-Man

    2011-01-01

    We propose a scheme to enable a controllable cross-Kerr interaction between microwave photons in a circuit quantum electrodynamics (QED) system. In this scheme we use two transmission-line resonators (TLRs) and one superconducting quantum interference device (SQUID) type charge qubit, which acts as an artificial atom. It is shown that in the dispersive regime of the circuit-QED system, a controllable cross-Kerr interaction can be obtained by properly preparing the initial state of the qubit, and a large cross-phase shift between two microwave fields in the two TLRs can then be reached. Based on this cross-Kerr interaction, we show how to create a macroscopic entangled state between the two TLRs.

  7. Data Acquisition and Control System for Broad-band Microwave Reflectometry on EAST

    CERN Document Server

    Wen, Fei; Zhang, Shoubiao; Kong, Defeng; Wang, Yuming; Han, Xiang; Qu, Hao; Gao, Xiang

    2014-01-01

    Microwave reflectometry is a non-intrusive plasma diagnostic tool which is widely applied in many fusion devices. In 2014, the microwave reflectometry on Experimental Advanced Superconducting Tokamak (EAST) had been upgraded to measure plasma density profile and fluctuation, which covered the frequency range of Q-band (32-56 GHz), V-band (47-76 GHz) and W-band (71-110 GHz). This paper presented a dedicated data acquisition and control system (DAQC) to meet the measurement requirements of high accuracy and temporal resolution. The DAQC consisted of two control modules, which integrated arbitrary waveform generation block (AWG) and trigger processing block (TP), and two data acquisition modules (DAQ) that was implemented base on the PXIe platform from National Instruments (NI). All the performance parameters had satisfied the requirements of reflectometry. The actual performance will be further examined in the experiments of EAST in 2014.

  8. Fabrication of Metarodielectric Photonic Crystals for Microwave Control

    Energy Technology Data Exchange (ETDEWEB)

    Takinami, Yohei; Kirihara, Soshu, E-mail: y-takinami@jwri.osaka-u.ac.jp [Smart Processing Reserch Center, Joining and Welding Reserch Institute, Osaka University (Japan)

    2011-05-15

    Photonic crystals have inspired a great deal of interests as key platforms for effective control of electromagnetic wave. They can suppress incident waves at a certain frequency by Bragg diffraction and exhibit photonic band gap. Photonic band gap structures can be applied for effective and compact wave control equipments. In this investigation, metal photonic crystals were fabricated by stereolithography and heat treatment process. Furthermore, metal-dielectric crystal was created through impregnation process of dielectric media. This concept of metal-dielectric photonic crystal is expected to contribute for not only the downsizing of electromagnetic wave devices, but also thermal flow control.

  9. Techniques for Microwave Near-Field Quantum Control of Trapped Ions

    Science.gov (United States)

    2013-01-31

    a solid copper support [Fig. 1(a)]. This support structure also holds a printed circuit board for in-vacuum filtering of the control potentials. We... circuit board is used for connecting both rf electrodes to a resonant quarter-wave step-up transformer (Qres 350, when loaded with the trap) [46...mm. Each microwave electrode is connected to a microstrip line on the filter board, which is soldered to a SMA jack on the input end. The other end of

  10. Tunable Diode Laser Sensor for Monitoring and Control of Harsh Combustion Environments

    Energy Technology Data Exchange (ETDEWEB)

    VonDrasek, William; Melsio-Pubill, Anna

    2006-05-30

    This work represents the collaborative effort between American Air Liquide and Physical Sciences, Inc. for developing a sensor based on near-IR tunable diode lasers (TDL). The multi-species capability of the sensor for simultaneous monitoring of CO, O2, and H2O concentration as well as gas temperature is ideal for in-situ monitoring on industrial furnaces. The chemical species targeted are fundamental for controlling the combustion space for improved energy efficiency, reduced pollutants, and improved product quality, when coupling the measurement to a combustion control system. Several add-on modules developed provide flexibility in the system configuration for handling different process monitoring applications. For example, the on-Demand Power Control system for the 1.5 ?m laser is used for high particle density exhaust streams where laser transmission is problematic. For long-distance signal collection a fiber optic communication system is used to reduce noise pick-up. Finally, hardened modules to withstand high ambient temperatures, immune to EMF interference, protection from flying debris, and interfaced with pathlength control laser beam shielding probes were developed specifically for EAF process monitoring. Demonstration of these different system configurations was conducted on Charter Steel's reheat furnace, Imco Recycling, Inc. (now Aleris International, Inc.) aluminum reverberatory furnace, and Gerdau Ameristeel's EAF. Measurements on the reheat furnace demonstrated zone monitoring with the measurement performed close to the steel billet. Results from the aluminum furnace showed the benefit of measuring in-situ near the bath. In this case, low-level furnace optimization was performed and demonstrated 5% fuel savings. Monitoring tests on the EAF off-gas demonstrated the level of industrialization of the sensor to survive the harsh EAF environment. Long-term testing on the EAF has been on-going for over 6 months with essentially zero maintenance

  11. Electromagnetic wave analogue of electronic diode

    OpenAIRE

    Shadrivov, Ilya V.; Powell, David A.; Kivshar, Yuri S.; Fedotov, Vassili A.; Zheludev, Nikolay I.

    2010-01-01

    An electronic diode is a nonlinear semiconductor circuit component that allows conduction of electrical current in one direction only. A component with similar functionality for electromagnetic waves, an electromagnetic isolator, is based on the Faraday effect of the polarization state rotation and is also a key component of optical and microwave systems. Here we demonstrate a chiral electromagnetic diode, which is a direct analogue of an electronic diode: its functionality is underpinned by ...

  12. Electromagnetic wave analogue of electronic diode

    OpenAIRE

    Shadrivov, Ilya V.; Powell, David A.; Kivshar, Yuri S.; Fedotov, Vassili A.; Zheludev, Nikolay I.

    2010-01-01

    An electronic diode is a nonlinear semiconductor circuit component that allows conduction of electrical current in one direction only. A component with similar functionality for electromagnetic waves, an electromagnetic isolator, is based on the Faraday effect of the polarization state rotation and is also a key component of optical and microwave systems. Here we demonstrate a chiral electromagnetic diode, which is a direct analogue of an electronic diode: its functionality is underpinned by ...

  13. Note: Efficient diode laser line narrowing using dual, feed-forward + feed-back laser frequency control

    Science.gov (United States)

    Lintz, M.; Phung, D. H.; Coulon, J.-P.; Faure, B.; Lévèque, T.

    2017-02-01

    We have achieved distributed feedback laser diode line narrowing by simultaneously acting on the diode current via a feed-back loop and on an external electrooptic phase modulator in feed-forward actuator. This configuration turns out to be very efficient in reaching large bandwidth in the phase correction: up to 15 MHz with commercial laser control units. About 98% of the laser power undergoes narrowing. The full width at half maximum of the narrowed optical spectrum is of less than 4 kHz. This configuration appears to be very convenient as the delay in the feed-forward control electronics is easily compensated for by a 20 m optical fiber roll.

  14. High-brightness organic light-emitting diodes for optogenetic control of Drosophila locomotor behaviour

    Science.gov (United States)

    Morton, Andrew; Murawski, Caroline; Pulver, Stefan R.; Gather, Malte C.

    2016-08-01

    Organic light emitting diodes (OLEDs) are in widespread use in today’s mobile phones and are likely to drive the next generation of large area displays and solid-state lighting. Here we show steps towards their utility as a platform technology for biophotonics, by demonstrating devices capable of optically controlling behaviour in live animals. Using devices with a pin OLED architecture, sufficient illumination intensity (0.3 mW.mm‑2) to activate channelrhodopsins (ChRs) in vivo was reliably achieved at low operating voltages (5 V). In Drosophila melanogaster third instar larvae expressing ChR2(H134R) in motor neurons, we found that pulsed illumination from blue and green OLEDs triggered robust and reversible contractions in animals. This response was temporally coupled to the timing of OLED illumination. With blue OLED illumination, the initial rate and overall size of the behavioural response was strongest. Green OLEDs achieved roughly 70% of the response observed with blue OLEDs. Orange OLEDs did not produce contractions in larvae, in agreement with the spectral response of ChR2(H134R). The device configuration presented here could be modified to accommodate other small model organisms, cell cultures or tissue slices and the ability of OLEDs to provide patterned illumination and spectral tuning can further broaden their utility in optogenetics experiments.

  15. Frequency Reconfigurable Circular Patch Antenna with an Arc-Shaped Slot Ground Controlled by PIN Diodes

    Directory of Open Access Journals (Sweden)

    Yao Chen

    2017-01-01

    Full Text Available In this paper, a compact frequency reconfigurable circular patch antenna with an arc-shaped slot loaded in the ground layer is proposed for multiband wireless communication applications. By controlling the ON/OFF states of the five PIN diodes mounted on the arc-shaped slot, the effective length of the arc-shaped slot and the effective length of antennas current are changed, and accordingly six-frequency band reconfiguration can be achieved. The simulated and measured results show that the antenna can operate from 1.82 GHz to 2.46 GHz, which is located in DCS1800 (1.71–1.88 GHz, UMTS (2.11–2.20 GHz, WiBro (2.3–2.4 GHz, and Bluetooth (2.4–2.48 GHz frequency bands and so forth. Compared to the common rectangular slot circular patch antenna, the proposed arc-shaped slot circular patch antenna not only has a better rotational symmetry with the circular patch and substrate but also has more compact size. For the given operating frequency at 1.82 GHz, over 55% area reduction is achieved in this design with respect to the common design with rectangular slot. Since the promising frequency reconfiguration, this antenna may have potential applications in modern multiband and multifunctional mobile communication systems.

  16. Improvement in Device Performance and Reliability of Organic Light-Emitting Diodes through Deposition Rate Control

    Directory of Open Access Journals (Sweden)

    Shun-Wei Liu

    2014-01-01

    Full Text Available We demonstrated a fabrication technique to reduce the driving voltage, increase the current efficiency, and extend the operating lifetime of an organic light-emitting diode (OLED by simply controlling the deposition rate of bis(10-hydroxybenzo[h]qinolinato beryllium (Bebq2 used as the emitting layer and the electron-transport layer. In our optimized device, 55 nm of Bebq2 was first deposited at a faster deposition rate of 1.3 nm/s, followed by the deposition of a thin Bebq2 (5 nm layer at a slower rate of 0.03 nm/s. The Bebq2 layer with the faster deposition rate exhibited higher photoluminescence efficiency and was suitable for use in light emission. The thin Bebq2 layer with the slower deposition rate was used to modify the interface between the Bebq2 and cathode and hence improve the injection efficiency and lower the driving voltage. The operating lifetime of such a two-step deposition OLED was 1.92 and 4.6 times longer than that of devices with a single deposition rate, that is, 1.3 and 0.03 nm/s cases, respectively.

  17. Low-leakage diode-triggered silicon controlled rectifier for electrostatic discharge protection in 0.18-μm CMOS process

    Institute of Scientific and Technical Information of China (English)

    Xiao-yang DU; Shu-rong DONG; Yan HAN; Ming-xu HUO; Da-hai HUANG

    2009-01-01

    A diode-triggered silicon controlled rectifier (DTSCR) is being developed as an electrostatic discharge (ESD) protection device for low voltage applications. However, DTSCR leaks high current during normal operation due to the Darlington effect of the triggering-assist diode string. In this study, two types of diode string triggered SCRs are designed for low leakage consideration; the modified diode string and composite polysilicon diode string triggered SCRs (MDTSCR & PDTSCR). Compared with the conventional DTSCR (CDTSCR), the MDTSCR has a much lower substrate leakage current with a relatively large silicon cost, and the PDTSCR has a much lower substrate leakage current with similar area and shows good leakage performance at a high temperature. Other DTSCR ESD properties are also investigated, especially regarding their layout, triggering voltage and failure current.

  18. Identifying microwave magnetic resonance in chiral elements for creation of controlled matched absorbing metastructures

    Science.gov (United States)

    Kraftmakher, G. A.; Butylkin, V. S.; Kazantsev, Yu. N.; Mal'tsev, V. P.; Temirov, Yu. Sh.

    2017-01-01

    It has been suggested a method for identifying and separating magnetic and electric microwave resonance responses of conductive chiral and bianisotropic elements by reflection of electromagnetic waves in the standing and traveling-wave modes. It has been observed experimentally (in waveguide) and confirmed numerically (in free space) that magnetic resonance, which is excited by microwave magnetic field h, and electric resonances, excited by electric field E, show drastically different resonance curves of reflection. These distinctions allow to identifying the magnetic resonance response and using magnetically excited elements for broadband matching of absorbers instead of traditional quarter-wavelength layer. We have fabricated and investigated matched absorbing metastructures which are controlled by voltage as well by light of remote laser pointer.

  19. Microwave engineering concepts and fundamentals

    CERN Document Server

    Khan, Ahmad Shahid

    2014-01-01

    Detailing the active and passive aspects of microwaves, Microwave Engineering: Concepts and Fundamentals covers everything from wave propagation to reflection and refraction, guided waves, and transmission lines, providing a comprehensive understanding of the underlying principles at the core of microwave engineering. This encyclopedic text not only encompasses nearly all facets of microwave engineering, but also gives all topics—including microwave generation, measurement, and processing—equal emphasis. Packed with illustrations to aid in comprehension, the book: •Describes the mathematical theory of waveguides and ferrite devices, devoting an entire chapter to the Smith chart and its applications •Discusses different types of microwave components, antennas, tubes, transistors, diodes, and parametric devices •Examines various attributes of cavity resonators, semiconductor and RF/microwave devices, and microwave integrated circuits •Addresses scattering parameters and their properties, as well a...

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

    KAUST Repository

    Ooi, Boon S.

    2016-12-29

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

  1. Quality control of flaxseed grain processed with microwave roasting heat treatment

    OpenAIRE

    Puvača, Nikola M.; Stanaćev, Vidica; Jajić, Igor; Lević, Jovanka D.; Glamočić, Dragan; Krstović, Saša Z.

    2013-01-01

    Aim of this study was to investigate effects of microwave roasting on basic chemical composition, crude protein solubility and amino acid composition of flaxseed grain. Flaxseed was microwaved in a microwave oven Samsung GE82N-B with LED display at 450W for 0, 1, 3 and 5 minutes. Microwave roasting during 5 minutes led to statistically significant (P

  2. Mirror deflection control for a confocal scanning laser microscope employing a time-modulated laser and a linear diode array

    Science.gov (United States)

    Aslund, Nils R.; Patwardhan, Ardan; Trepte, Oliver

    1994-04-01

    A mirror deflection device for a CSLM has been developed. It performs repetitive scanning according to a preset waveform which can be chosen arbitrarily. It can also be used to perform stationary positioning at arbitrarily chosen points. A digital memory, comprising dual banks, is used to allow switching from one actuating waveform to another. The movement of the mirror is recorded very accurately. A burst of sequential pulse from a diode laser is deflected by the mirror and recorded by means of a linear diode array. The target pattern is analyzed digitally. The objective is to implement a control strategy whereby a new actuating waveform can be derived in order to correct any deviation between the desired waveform and the recorded one. Some results obtained with the device are reported. Foreseen applications encompass spectral analysis of selected regions and kinetic studies where a trade-off between speed and number of image points is necessary.

  3. Efficacy of high intensity diode laser as an adjunct to non-surgical periodontal treatment: a randomized controlled trial.

    Science.gov (United States)

    De Micheli, Giorgio; de Andrade, Ana Karina Pinto; Alves, Vanessa Tubero Euzebio; Seto, Marcio; Pannuti, Cláudio Mendes; Cai, Silvana

    2011-01-01

    The high intensity diode laser has been studied in periodontics for the reduction of subgingival bacteria in non-surgical treatment. Our study evaluated the bacterial effect as well as changes in periodontal clinical parameters promoted by root scaling and planing associated with this wavelength. Twenty-seven patients randomly assigned in two groups underwent root scaling and planing on the tested sites, and only the experimental group received the diode laser irradiation. Among the clinical parameters studied, the clinical probing depth (CPD) and the clinical attachment level (CAL) resulted in significant enhancement in the control group when compared with the experimental group (P = 0.014 and P = 0.039, respectively). The results were similar for both groups regarding the plaque index (PI) and bleeding on probing (BP). No significant difference in the microbiological parameters was observed between the control and experimental groups. It was possible to conclude that the high power diode laser adjunct to the non-surgical periodontal treatment did not promote additional effects to the conventional periodontal treatment.

  4. Microwave array applicator for radiometry-controlled superficial hyperthermia

    Science.gov (United States)

    Stauffer, Paul R.; Jacobsen, Svein; Neuman, Daniel

    2001-06-01

    Hyperthermia therapy has been shown clinically effective for a variety of skin diseases but current heating equipment is inadequate for most patients. This effort describes the design and performance of a flexible microstrip array applicator intended for heating large regions of tissue over contoured anatomy while at the same time monitoring temperature of the underlying tissue by non-invasive radiometric sensing of blackbody radiation from the heated volume. For this dual purpose applicator, an array of broadband Archimedean spiral receive antennas is integrated into an array of Dual Concentric Conductor heating apertures. Applicator heating uniformity is assessed with electric field scans in homogenous muscle phantoms and with measured temperature distributions in clinical treatments of chestwall recurrence of breast carcinoma. The data demonstrate precisely controlled heating out to the perimeter of large (40 x 13 cm2) multiaperture conformal array applicators. Capabilities of the radiometry system are assessed by correlation of brightness temperatures measured in phantom loads of known temperature distribution as seen through an intervening 5 mm thick water bolus at constant 40°C. The radiometer demonstrates excellent sensitivity and an accuracy of +0.1-0.45°C for temperature measurements up to 5 cm deep in phantom when using a one dimensional weighting function analysis and up to 6 independent 500 MHz bandwidths within the 1-4 GHz range. The data clearly indicate that both heating and radiometric thermometry are possible using the same thin and flexible printed circuit board microstrip array applicator. Once development is complete, this dual mode conformal array applicator with multiplexed radiometric display system should provide significantly improved uniformity and ease of heating large area superficial tissue disease.

  5. Single-Molecule Diodes with High On/Off Ratios Through Environmental Control

    Science.gov (United States)

    Capozzi, Brian; Xia, Jianlong; Dell, Emma; Adak, Olgun; Liu, Zhen-Fei; Neaton, Jeffrey; Campos, Luis; Venkataraman, Latha

    2015-03-01

    Single-Molecule diodes were first proposed with an asymmetric molecule comprising a donor-bridge-acceptor architecture to mimic a semiconductor p-n junction. Progress in molecular electronics has led to the realization of several single-molecule diodes; these have relied on asymmetric molecular backbones, asymmetric molecule-electrode linkers, or asymmetric electrode materials. Despite these advances, molecular diodes have had limited potential for functional applications due to several pitfalls, including low rectification ratios (``on''/``off'' current ratios environment instead of an asymmetric molecule, we reproducibly achieve high rectification ratios at low operating voltages for molecular junctions based on a family of symmetric small-gap molecules. This technique serves as an unconventional approach for developing functional molecular-scale devices and probing their charge transport characteristics. Furthermore, this technique should be applicable to other nanoscale devices, providing a general route for tuning device properties.

  6. Electromagnetic wave analogue of electronic diode

    CERN Document Server

    Shadrivov, Ilya V; Kivshar, Yuri S; Fedotov, Vassili A; Zheludev, Nikolay I

    2010-01-01

    An electronic diode is a nonlinear semiconductor circuit component that allows conduction of electrical current in one direction only. A component with similar functionality for electromagnetic waves, an electromagnetic isolator, is based on the Faraday effect of the polarization state rotation and is also a key component of optical and microwave systems. Here we demonstrate a chiral electromagnetic diode, which is a direct analogue of an electronic diode: its functionality is underpinned by an extraordinary strong nonlinear wave propagation effect in the same way as electronic diode function is provided by a nonlinear current characteristic of a semiconductor junction. The effect exploited in this new electromagnetic diode is an intensity-dependent polarization change in an artificial chiral metamolecule. This microwave effect exceeds a similar optical effect previously observed in natural crystals by more than 12 orders of magnitude and a direction-dependent transmission that differing by a factor of 65.

  7. Microwave Semiconductor Equipment Produced in Poland,

    Science.gov (United States)

    1984-01-20

    lQal signal source in other devices. Microwave Transistors As a result of work in the field of microwave transistors , the technology for pnp ...is now commonly carried out on transistors and microwave subsystems. The results of the labors of the DM section connected with the new devices and...level of employment Illustration 2. Microwave diodes and semiconductor transistors presently produced in the ITE (DM section) The Construction and

  8. Red and blue pulse timing control for pulse width modulation light dimming of light emitting diodes for plant cultivation.

    Science.gov (United States)

    Shimada, Aoi; Taniguchi, Yoshio

    2011-09-02

    A pulse width modulation (PWM) light dimming system containing red and blue light emitting diodes was designed and constructed. Cultivation of the plant Arabidopsis thaliana under various light dimming wave patterns was compared. Control of the pulse timing (phase of wave pattern) between red and blue light in PWM light dimming was examined. Different plant growth was obtained by changing the phase of red and blue pulses. Pulse timing control of PWM light dimming for plant cultivation has the potential to act as a method for probing photosynthesis. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Characterization of a Digital Microwave Radiometry System for Noninvasive Thermometry using Temperature Controlled Homogeneous Test Load

    Science.gov (United States)

    Arunachalam, K; Stauffer, P R; Maccarini, PF; Jacobsen, S; Sterzer, F

    2009-01-01

    Microwave radiometry has been proposed as a viable noninvasive thermometry approach for monitoring subsurface tissue temperatures and potentially controlling power levels of multielement heat applicators during clinical hyperthermia treatments. With the evolution of technology, several analog microwave radiometry devices have been developed for biomedical applications. In this paper, we describe a digital microwave radiometer with built-in electronics for signal processing and automatic self-calibration. Performance of the radiometer with an Archimedean spiral receive antenna is evaluated over a bandwidth of 3.7–4.2GHz in homogeneous and layered water test loads. Controlled laboratory experiments over the range of 30–50°C characterize measurement accuracy, stability, repeatability and penetration depth sensitivity. The ability to sense load temperature through an intervening water coupling bolus of 6mm thickness is also investigated. To assess clinical utility and sensitivity to electromagnetic interference (EMI), experiments are conducted inside standard clinical hyperthermia treatment rooms with no EM shielding. The digital radiometer provided repeatable measurements with 0.075°C resolution and standard deviation of 0.217°C for homogeneous and layered tissue loads at temperatures between 32–45°C. Within the 3.7–4.2GHz band, EM noise rejection was good other than some interference from overhead fluorescent lights in the same room as the radiometer. The system response obtained for ideal water loads suggests that this digital radiometer should be useful for estimating subcutaneous tissue temperatures under a 6mm waterbolus used during clinical hyperthermia treatments. The accuracy and stability data obtained in water test loads of several configurations support our expectation that single band radiometry should be sufficient for sub-surface temperature monitoring and power control of large multielement array superficial hyperthermia applicators. PMID

  10. Land Surface Microwave Emissivities Derived from AMSR-E and MODIS Measurements with Advanced Quality Control

    Science.gov (United States)

    Moncet, Jean-Luc; Liang, Pan; Galantowicz, John F.; Lipton, Alan E.; Uymin, Gennady; Prigent, Catherine; Grassotti, Christopher

    2011-01-01

    A microwave emissivity database has been developed with data from the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) and with ancillary land surface temperature (LST) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the same Aqua spacecraft. The primary intended application of the database is to provide surface emissivity constraints in atmospheric and surface property retrieval or assimilation. An additional application is to serve as a dynamic indicator of land surface properties relevant to climate change monitoring. The precision of the emissivity data is estimated to be significantly better than in prior databases from other sensors due to the precise collocation with high-quality MODIS LST data and due to the quality control features of our data analysis system. The accuracy of the emissivities in deserts and semi-arid regions is enhanced by applying, in those regions, a version of the emissivity retrieval algorithm that accounts for the penetration of microwave radiation through dry soil with diurnally varying vertical temperature gradients. These results suggest that this penetration effect is more widespread and more significant to interpretation of passive microwave measurements than had been previously established. Emissivity coverage in areas where persistent cloudiness interferes with the availability of MODIS LST data is achieved using a classification-based method to spread emissivity data from less-cloudy areas that have similar microwave surface properties. Evaluations and analyses of the emissivity products over homogeneous snow-free areas are presented, including application to retrieval of soil temperature profiles. Spatial inhomogeneities are the largest in the vicinity of large water bodies due to the large water/land emissivity contrast and give rise to large apparent temporal variability in the retrieved emissivities when satellite footprint locations vary over time. This issue will be dealt with in the future by

  11. Land Surface Microwave Emissivities Derived from AMSR-E and MODIS Measurements with Advanced Quality Control

    Science.gov (United States)

    Moncet, Jean-Luc; Liang, Pan; Galantowicz, John F.; Lipton, Alan E.; Uymin, Gennady; Prigent, Catherine; Grassotti, Christopher

    2011-01-01

    A microwave emissivity database has been developed with data from the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) and with ancillary land surface temperature (LST) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the same Aqua spacecraft. The primary intended application of the database is to provide surface emissivity constraints in atmospheric and surface property retrieval or assimilation. An additional application is to serve as a dynamic indicator of land surface properties relevant to climate change monitoring. The precision of the emissivity data is estimated to be significantly better than in prior databases from other sensors due to the precise collocation with high-quality MODIS LST data and due to the quality control features of our data analysis system. The accuracy of the emissivities in deserts and semi-arid regions is enhanced by applying, in those regions, a version of the emissivity retrieval algorithm that accounts for the penetration of microwave radiation through dry soil with diurnally varying vertical temperature gradients. These results suggest that this penetration effect is more widespread and more significant to interpretation of passive microwave measurements than had been previously established. Emissivity coverage in areas where persistent cloudiness interferes with the availability of MODIS LST data is achieved using a classification-based method to spread emissivity data from less-cloudy areas that have similar microwave surface properties. Evaluations and analyses of the emissivity products over homogeneous snow-free areas are presented, including application to retrieval of soil temperature profiles. Spatial inhomogeneities are the largest in the vicinity of large water bodies due to the large water/land emissivity contrast and give rise to large apparent temporal variability in the retrieved emissivities when satellite footprint locations vary over time. This issue will be dealt with in the future by

  12. Simultaneous phase and morphology controllable synthesis of copper selenide films by microwave-assisted nonaqueous approach

    Science.gov (United States)

    Li, Jing; Fa, Wenjun; Li, Yasi; Zhao, Hongxiao; Gao, Yuanhao; Zheng, Zhi

    2013-02-01

    Copper selenide films with different phase and morphology were synthesized on copper substrate through controlling reaction solvent by microwave-assisted nonaqueous approach. The films were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The result showed that the pure films could be obtained using cyclohexyl alcohol or benzyl alcohol as solvent. The cubic Cu2-xSe dendrites were synthesized in cyclohexyl alcohol reaction system and hexagonal CuSe flaky crystals were obtained with benzyl alcohol as solvent.

  13. Multicomponent reactions for synthesis of bioactive polyheterocyclic ring systems under controlled microwave irradiation

    Directory of Open Access Journals (Sweden)

    Eman M.H. Abbas

    2014-11-01

    Full Text Available The multi-component reaction of 1-benzothiopyran-4-ones with heterocyclic amines and dimethylformamide-dimethylacetal (DMFDMA in DMF at 150 °C under controlled microwave heating afforded novel poly-heterocyclic ring systems. Also, reaction of 3-dimethylaminomethylene-1-benzothiopyran-4-one with activemethylene derivatives was investigated. The structure of all products was established on the bases of spectral data and elemental analyses and alternative synthesis if possible. The prepared compounds were screened for their antitumor activity against HCT-116 “colon” cancer cell line and some derivatives showed promising activity.

  14. Final environmental assessment for vegetation control at VHF stations, microwave stations, electrical substations, and pole yards

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-10-13

    Southwestern Power Adm. operates very high frequency (VHF) and microwave radio stations, electrical substations, and pole yards for electric power transmission throughout AR, MO, and OK. Vegetation growth at the stations must be suppressed for safety of operation and personnel. Southwestern has been using a combination of mechanical/manual and herbicide control for this purpose; Federally- mandated reductions in staff and budgetary resources require Southwestern to evaluate all potentially efficient methods for vegetation control. Three alternatives were examined: no action, mechanical/manual control, and (proposed) a combination of mechanical/manual and herbicide control. Environmental impacts on air and water quality, wetlands, wildlife, endangered species, archaeological and other resources, farmland, human health, transportation, etc. were evaluated.

  15. Novel diode-based laser system for combined transcutaneous monitoring and computer-controlled intermittent treatment of jaundiced neonates

    Science.gov (United States)

    Hamza, Mostafa; El-Ahl, Mohammad H. S.; Hamza, Ahmad M.

    2001-06-01

    The high efficacy of laser phototherapy combined with transcutaneous monitoring of serum bilirubin provides optimum safety for jaundiced infants from the risk of bilirubin encephalopathy. In this paper the authors introduce the design and operating principles of a new laser system that can provide simultaneous monitoring and treatment of several jaundiced babies at one time. The new system incorporates diode-based laser sources oscillating at selected wavelengths to achieve both transcutaneous differential absorption measurements of bilirubin concentration in addition to the computer controlled intermittent laser therapy through a network of optical fibers. The detailed description and operating characteristics of this system are presented.

  16. Magnetically controlled zero-index metamaterials based on ferrite at microwave frequencies

    Science.gov (United States)

    Wang, Yongxing; Qin, Yue; Sun, Zhouzhou; Xu, Ping

    2016-10-01

    Magnetically controlled zero-index metamaterials have numerous applications due to their wide tunable range and sensitive response to bias magnetic field. In this paper, magnetically controlled index-near-zero metamaterials and μ-near-zero metamaterials based on ferrite have been realized. Combining these proposed metamaterials with proper waveguide structures, we have obtained a tunable index-near-zero structure and a tunable μ-near-zero structure, respectively. For both structures, transmittance can be tuned by bias magnetic field in a wide range with high sensitivity. Our proposed tunable zero-index metamaterial structures have potential applications in microwave devices such as switches, sensors and modulators. Besides, the tunable μ-near-zero structure possesses a multifrequency tunneling effect and can be used to implement a tunable filter.

  17. A general modelling and control algorithm of a three-phase multilevel diode clamped inverter by means of a direct space vector control

    Science.gov (United States)

    Bouhali, O.; Francois, B.; Berkouk, E. M.; Saudemont, C.

    2005-07-01

    This paper presents a simple and general direct modulation strategy that enables to copy directly modulated waveforms onto output voltages of a multilevel three-phase Diode Clamped Inverter (DCI). A general modelling of this converter is presented. A space vector scheme is developed without using Park transforms. Based on this algorithm, the location of the reference voltage vector is determined and the voltage vectors for the modulation are deduced. Simultaneously, their durations are calculated. The proposed algorithm is general and can be directly applied to a (n+1) levels inverter independently on its topology (Diode Clamped Inverter, Neutral Point Clamped, Flying Capacitor Inverter...). To verify this algorithm, both control algorithms of a 5-level DCI and a 11-level DCI are considered and simulation results are given.

  18. Preliminary Study on Controlling Black Fungi Dwelling on Stone Monuments by Using a Microwave Heating System

    Directory of Open Access Journals (Sweden)

    Oana-Adriana CUZMAN

    2013-06-01

    Full Text Available Microcolonial black fungi have their natural ecological niche on rocks and walls of hypogean environments, playing an important role in the deterioration of materials and aesthetical alteration of monumental stones and mortars. Three black fungi (Sarcinomyces sp., Pithomyces sp. and Scolecobasidium sp. have been isolated from cultural assets of historical interest. These fungal strains have been used to test the microwave heating method as a new control methodology for eradicating the fungal biological growth on cultural stone artifacts. This methodology is based on a 2.45 GHz microwave electromagnetic radiation, generated by a new apparatus with an appropriate applicator. The first results showed the best dose of 65°C for three minutes, for all the investigated fungal strains. This methodology is very promising because is safety for the operator and the environment, and can be easily applied on site. The use of this method to kill biodeteriogens can avoid the application of chemicals formulates potentially dangerous for substrates and environment.

  19. Controlling the magnetic field sensitivity of atomic clock states by microwave dressing

    CERN Document Server

    Sárkány, L; Hattermann, H; Fortágh, J

    2014-01-01

    We demonstrate control of the differential Zeeman shift between clock states of ultracold rubidium atoms by means of non-resonant microwave dressing. Using the dc-field dependence of the microwave detuning, we suppress the first and second order differential Zeeman shift in magnetically trapped $^{87}$Rb atoms. By dressing the state pair 5S$_{1/2} F= 1, m_F = -1$ and $F= 2, m_F = 1$, a residual frequency spread of <0.1 Hz in a range of 100 mG around a chosen magnetic offset field can be achieved. This is one order of magnitude smaller than the shift of the bare states at the magic field of the Breit-Rabi parabola. We further identify double magic points, around which the clock frequency is insensitive to fluctuations both in the magnetic field and the dressing Rabi frequency. The technique is compatible with chip-based cold atom systems and allows the creation of clock and qubit states with reduced sensitivity to magnetic field noise.

  20. Design of Controlled Release Non-erodible Polymeric Matrix Tablet Using Microwave Oven-assisted Sintering Technique.

    Science.gov (United States)

    Patel, Dm; Patel, Bk; Patel, Ha; Patel, Cn

    2011-07-01

    The objective of the present study was to evaluate the effect of sintering condition on matrix formation and subsequent drug release from polymer matrix tablet for controlled release. The present study highlights the use of a microwave oven for the sintering process in order to achieve more uniform heat distribution with reduction in time required for sintering. We could achieve effective sintering within 8 min which is very less compared to conventional hot air oven sintering. The tablets containing the drug (propranolol hydrochloride) and sintering polymer (eudragit S-100) were prepared and kept in a microwave oven at 540 watt, 720 watt and 900 watt power for different time periods for sintering. The sintered tablets were evaluated for various tablet characteristics including dissolution study. Tablets sintered at 900 watt power for 8 min gave better dissolution profile compared to others. We conclude that microwave oven sintering is better than conventional hot air oven sintering process in preparation of controlled release tablets.

  1. Novel Design Integrating a Microwave Applicator into a Crystallizer for Rapid Temperature Cycling. A Direct Nucleation Control Study

    Science.gov (United States)

    2017-01-01

    The control of nucleation in crystallization processes is a challenging task due to the often lacking knowledge on the process kinetics. Inflexible (predetermined) control strategies fail to grow the nucleated crystals to the desired quality because of the variability in the process conditions, disturbances, and the stochastic nature of crystal nucleation. Previously, the concept of microwave assisted direct nucleation control (DNC) was demonstrated in a laboratory setup to control the crystal size distribution in a batch crystallization process by manipulating the number of particles in the system. Rapid temperature cycling was used to manipulate the super(under)saturation and hence the number of crystals. The rapid heating response achieved with the microwave heating improved the DNC control efficiency, resulting in halving of the batch time. As an extension, this work presents a novel design in which the microwave applicator is integrated in the crystallizer, hence avoiding the external loop though the microwaves oven. DNC implemented in the 4 L unseeded crystallizer, at various count set points, resulted in strong efficiency enhancement of DNC, when compared to the performance with a slow responding system. The demonstrated crystallizer design is a basis for extending the enhanced process control opportunity to other applications. PMID:28729813

  2. Production of a coherent pair of light beams with a microwave frequency difference from a single extended-cavity diode laser.

    Science.gov (United States)

    Yim, Sin Hyuk; Cho, D

    2010-02-01

    We produced a pair of coherent laser beams with a 3-GHz frequency difference by optically phase locking two modes from a single, multimode extended-cavity diode laser. This method is complementary to either a direct modulation or an optical phase locking of two independent lasers. A large differential frequency shift between the two modes of the laser allows efficient phase locking. We developed a simple theory to account for the large differential frequency shift. Allan deviation of the beat frequency when the two modes are phase-locked drops as an inverse of the measurement time and it reaches 10(-14) when the time is 1 h. Coherent population trapping spectroscopy of Rb atoms using the phase-locked beams resulted in a spectrum as narrow as that of the case using direct modulation by a stable frequency synthesizer.

  3. Desired Control of Mutually Delay-Coupled Diode Lasers near Phase-flip Transition Regimes

    CERN Document Server

    Kumar, Pramod

    2013-01-01

    We investigate zero-lag synchronization (ZLS) between delay-coupled diode lasers system with mutual optical injection in a face-to-face configuration. We observed numerical evidence of such ZLS without using any relay element or mediating laser. In addition, simulation also demonstrate that this kind of robust ZLS occurs around the phase flip transition regimes where in-phase and anti-phase oscillations coexist due to delayed coupling induced modulation of the phase-amplitude coupling factor {\\alpha}. Our finding could be implemented in highly secured optical communication network as well as the understanding of the occurrence of such ZLS in the neural network functionality.

  4. Control of dynamical instability in semiconductor quantum nanostructures diode lasers: Role of phase-amplitude coupling

    Science.gov (United States)

    Kumar, P.; Grillot, F.

    2013-07-01

    We numerically investigate the complex nonlinear dynamics for two independently coupled laser systems consisting of (i) mutually delay-coupled edge emitting diode lasers and (ii) injection-locked quantum nanostructures lasers. A comparative study in dependence on the dynamical role of α parameter, which determine the phase-amplitude coupling of the optical field, in both the cases is probed. The variation of α lead to conspicuous changes in the dynamics of both the systems, which are characterized and investigated as a function of optical injection strength η for the fixed coupled-cavity delay time τ. Our analysis is based on the observation that the cross-correlation and bifurcation measures unveil the signature of enhancement of amplitude-death islands in which the coupled lasers mutually stay in stable phase-locked states. In addition, we provide a qualitative understanding of the physical mechanisms underlying the observed dynamical behavior and its dependence on α. The amplitude death and the existence of multiple amplitude death islands could be implemented for applications including diode lasers stabilization.

  5. Voltage controlled modification of flux closure domains in planar magnetic structures for microwave applications

    Energy Technology Data Exchange (ETDEWEB)

    Parkes, D. E.; Beardsley, R.; Edmonds, K. W.; Campion, R. P.; Gallagher, B. L.; Rushforth, A. W., E-mail: Stuart.Cavill@york.ac.uk, E-mail: Andrew.Rushforth@nottingham.ac.uk [School of Physics and Astronomy, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Bowe, S. [School of Physics and Astronomy, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Diamond Light Source, Chilton, Didcot, Oxfordshire OX11 0DE (United Kingdom); Isakov, I.; Warburton, P. A. [London Centre of Nanotechnology, University College London, London WC1H 0AH (United Kingdom); Cavill, S. A., E-mail: Stuart.Cavill@york.ac.uk, E-mail: Andrew.Rushforth@nottingham.ac.uk [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Diamond Light Source, Chilton, Didcot, Oxfordshire OX11 0DE (United Kingdom)

    2014-08-11

    Voltage controlled modification of the magnetocrystalline anisotropy in a hybrid piezoelectric/ferromagnet device has been studied using Photoemission Electron Microscopy with X-ray magnetic circular dichroism as the contrast mechanism. The experimental results demonstrate that the large magnetostriction of the epitaxial Fe{sub 81}Ga{sub 19} layer enables significant modification of the domain pattern in laterally confined disc structures. In addition, micromagnetic simulations demonstrate that the strain induced modification of the magnetic anisotropy allows for voltage tuneability of the natural resonance of both the confined spin wave modes and the vortex motion. These results demonstrate the possibility for using voltage induced strain in low-power voltage tuneable magnetic microwave oscillators.

  6. Implementation of dosimetric quality control on IMRT and VMAT treatments in radiotherapy using diodes; Implementacion de control de calidad dosimetrico en tratamientos de IMRT y VMAT en radioterapia usando diodos

    Energy Technology Data Exchange (ETDEWEB)

    Gonzales, A.; Garcia, B.; Ramirez, J.; Marquina, J., E-mail: andres.gonzales@aliada.com.pe [ALIADA, Oncologia Integral, Av. Jose Galvez Barrenechea 1044, San Isidro, Lima 27 (Peru)

    2014-08-15

    To implement quality control of IMRT and VMAT treatments Rapid Arc radiotherapy using diode array. Were tested 90 patients with IMRT and VMAT Rapid Arc, comparing the planned dose to the dose administered, used the Map-Check-2 and Arc-Check of Sun Nuclear, they using the gamma factor for calculating and using comparison parameters 3% / 3m m. The statistic shows that the quality controls of the 90 patients analyzed, presented a percentage of diodes that pass the test between 96,7% and 100,0% of the irradiated diodes. Implemented in Clinical ALIADA Oncologia Integral, the method for quality control of IMRT and VMAT treatments Rapid Arc radiotherapy using diode array. (Author)

  7. Near-infrared superluminescent diode using stacked self-assembled InAs quantum dots with controlled emission wavelengths

    Science.gov (United States)

    Ozaki, Nobuhiko; Yasuda, Takuma; Ohkouchi, Shunsuke; Watanabe, Eiichiro; Ikeda, Naoki; Sugimoto, Yoshimasa; Hogg, Richard A.

    2014-01-01

    A near-infrared superluminescent diode (SLD) using stacked InAs/GaAs quantum dots (QDs) was developed. The emission wavelength of each QD layer was controlled by varying the thickness of a strain-reducing layer deposited on the QD. The controlled ground state emission peaks enabled formation of a dipless broadband spectrum with the contributions of the first excited state emissions. The bandwidth of the resulting emission was approximately 170 nm with a peak wavelength of 1280 nm. The integrated electroluminescence intensity exhibited a superlinear relation with respect to the injected current density, indicating an SLD emission behavior owing to contributions of stimulated emissions from QDs. The developed broadband SLD was found to be suitable as a potential light source for optical coherence tomography (OCT) leading to improved resolution of OCT images. The axial resolution estimated from the Fourier-transformed spectrum is 4.1 µm.

  8. 3D microwave cavity with magnetic flux control and enhanced quality factor

    Energy Technology Data Exchange (ETDEWEB)

    Reshitnyk, Yarema [The University of Queensland, School of Mathematics and Physics, St Lucia (Australia); Jerger, Markus [The University of Queensland, ARC Centre of Excellence for Engineered Quantum Systems, 4072 (Australia); Fedorov, Arkady [The University of Queensland, School of Mathematics and Physics, St Lucia (Australia); The University of Queensland, ARC Centre of Excellence for Engineered Quantum Systems, 4072 (Australia)

    2016-12-15

    Three-dimensional (3D) microwave cavities have been extensively used for coupling and interacting with superconducting quantum bits (qubits), providing a versatile platform for quantum control experiments and for realizing hybrid quantum systems. While having high quality factors (>10{sup 6}) superconducting cavities do not permit magnetic field control of qubits. In contrast, cavities made of normal metals are transparent to magnetic fields, but experience lower quality factors (∝10{sup 4}). We have created a hybrid cavity which is primarily composed of aluminium but also contains a small copper insert reaching the internal quality factor of ≅10{sup 5}, an order of magnitude improvement over all previously tested normal metal cavities. In order to demonstrate precise magnetic control, we performed spectroscopy of three superconducting qubits, where individual control of each qubit's frequency was exerted with small external wire coils. An improvement in quality factor and magnetic field control makes this 3D hybrid cavity an attractive new element for circuit quantum electrodynamics experiments. (orig.)

  9. Light-emitting Diodes

    Science.gov (United States)

    Opel, Daniel R.; Hagstrom, Erika; Pace, Aaron K.; Sisto, Krisanne; Hirano-Ali, Stefanie A.; Desai, Shraddha

    2015-01-01

    Background: In the early 1990s, the biological significance of light-emitting diodes was realized. Since this discovery, various light sources have been investigated for their cutaneous effects. Study design: A Medline search was performed on light-emitting diode lights and their therapeutic effects between 1996 and 2010. Additionally, an open-label, investigator-blinded study was performed using a yellow light-emitting diode device to treat acne, rosacea, photoaging, alopecia areata, and androgenetic alopecia. Results: The authors identified several case-based reports, small case series, and a few randomized controlled trials evaluating the use of four different wavelengths of light-emitting diodes. These devices were classified as red, blue, yellow, or infrared, and covered a wide range of clinical applications. The 21 patients the authors treated had mixed results regarding patient satisfaction and pre- and post-treatment evaluation of improvement in clinical appearance. Conclusion: Review of the literature revealed that differing wavelengths of light-emitting diode devices have many beneficial effects, including wound healing, acne treatment, sunburn prevention, phototherapy for facial rhytides, and skin rejuvenation. The authors’ clinical experience with a specific yellow light-emitting diode device was mixed, depending on the condition being treated, and was likely influenced by the device parameters. PMID:26155326

  10. Dynamic Control of Microwave Plasma Sources for Material Processing by Using Hyper-Simulation

    Science.gov (United States)

    Yasaka, Yasuyoshi; Tsuji, Akihiro

    2010-11-01

    Uniformity of etching or deposition over a wafer is one of the key features for plasma processing with large-size wafers. The uniformity can be measured as a result of a process, and correction or improvement of the uniformity is made by changing device parameters such as power levels, gas flow rates, timings, and so on. Evaluation and control are, however, not combined or unified as a problem of plasma physics. They are assigned as the input and output of a black box of empirical transfer function obtained by expert systems or neural networks. We are going to establish a novel control system based on physics, in which a fluid simulation is used to obtain a power deposition profile necessary to produce the two-dimensional density distribution of desire. A control system of a microwave slot antenna then changes power distribution dynamically according to the output of the simulation. It should be noted that this simulation has inputs and outputs opposite to conventional ones, which, we call hyper-simulation, is one of the novel features of the control system.

  11. Control of dynamical instability in semiconductor quantum nanostructures diode lasers: role of phase-amplitude coupling

    CERN Document Server

    Kumar, Pramod

    2013-01-01

    We numerically investigate the complex nonlinear dynamics for two independent coupled lasers systems consisting of (i) mutually delay-coupled edge emitting diode lasers and (ii) injection-locked quantum nano-structures lasers. A comparative study in dependence on the dynamical role of alpha parameter, that determines phase-amplitude coupling of the optical field, in both the cases is probed. The variation of alpha leads to conspicuous changes of the dynamics of both the systems, which are characterized and investigated as a function of optical injection strength for the fixed coupled-cavity delay time. Our analysis is based on the observation that the cross-correlation and bifurcation measures unveil the signature of enhancement of amplitude-death islands in which the coupled lasers mutually stay in stable phase-locked states. In addition, we provide a qualitative understanding of the physical mechanisms underlying the observed dynamical behavior and its dependence on alpha. The amplitude death and existence ...

  12. Mushroom-type structures with the wires connected through diodes: Theory and applications

    Science.gov (United States)

    Forouzmand, Ali; Kaipa, Chandra S. R.; Yakovlev, Alexander B.

    2016-07-01

    In this paper, we establish a general formalism to quantify the interaction of electromagnetic waves with mushroom-type structures (high impedance surface and bi-layer) with diodes inserted along the direction of the wires. The analysis is carried out using the nonlocal homogenization model for the mushroom structure with the generalized additional boundary conditions at the connection of the wires to diodes. We calculate numerically the magnitude and phase of the reflected/transmitted fields in the presence of an ideal and realistic PIN diodes. It is observed that the reflection/transmission characteristics of the mushroom-type structures can be controlled by tuning the working states of the integrated PIN diodes. We realize a structure with a multi-diode switch to minimize the undesired transmission for a particular incident angle. In addition, a dual-band subwavelength imaging lens is designed based on the resonant amplification of evanescent waves, wherein the operating frequency can be tuned by changing the states of the PIN diodes. The analytical results are verified with the full-wave electromagnetic solver CST Microwave Studio, showing a good agreement.

  13. IMPATT diodes. Citations from the NTIS data base

    Science.gov (United States)

    Reed, W. E.

    1980-04-01

    Government sponsored research reports are cited covering the design, characterization, and applications of IMPATT diodes. Topics include reliability, power handling, properties, noise, fabrication, and radiation effects. The use of silicon and gallium arsenide IMPATT diodes for microwave generation and amplification is included. This updated bibliography contains 182 abstracts, 14 of which are new entries to the previous edition.

  14. Microwave photonics processing controlling the speed of light in semiconductor waveguides

    DEFF Research Database (Denmark)

    Xue, Weiqi; Chen, Yaohui; Sales, Salvador;

    2009-01-01

    We review the theory of slow and fast light effect in semiconductor waveguides and potential applications of these effects in microwave photonic systems as RF phase shifters. Recent applications as microwave photonic filters is presented. Also, in the presentation more applications like...... optoelectronic oscillators and arbitrary waveform generators will be described. Some work related to the noise and distortion will also be discussed...

  15. Identification procedures for the charge-controlled nonlinear noise model of microwave electron devices

    Science.gov (United States)

    Filicori, Fabio; Traverso, Pier Andrea; Florian, Corrado; Borgarino, Mattia

    2004-05-01

    The basic features of the recently proposed Charge-Controlled Non-linear Noise (CCNN) model for the prediction of low-to-high-frequency noise up-conversion in electron devices under large-signal RF operation are synthetically presented. It is shown that the different noise generation phenomena within the device can be described by four equivalent noise sources, which are connected at the ports of a "noiseless" device model and are non-linearly controlled by the time-varying instantaneous values of the intrinsic device voltages. For the empirical identification of the voltage-controlled equivalent noise sources, different possible characterization procedures, based not only on conventional low-frequency noise data, but also on different types of noise measurements carried out under large-signal RF operating conditions are discussed. As an example of application, the measurement-based identification of the CCNN model for a GaInP heterojunction bipolar microwave transistor is presented. Preliminary validation results show that the proposed model can describe with adequate accuracy not only the low-frequency noise of the HBT, but also its phase-noise performance in a prototype VCO implemented by using the same monolithic GaAs technology.

  16. A randomized controlled clinical trial to evaluate the adjunct effectiveness of diode laser gingivectomy in maintaining periodontal health during orthodontic treatment

    OpenAIRE

    To, TNF; Rabie, BM; Wong, RWK; McGrath, CP

    2012-01-01

    AIM: To evaluate the effectiveness of adjunctive diode laser gingivectomy in periodontal health management among orthodontic patients. MATERIALS AND METHODS: Thirty patients with gingival enlargement were randomized into two groups. The control group received non-surgical periodontal treatment (NSPT). The test group received NSPT and adjunct…

  17. Microwave-controlled facile synthesis of well-defined PbS hexapods.

    Science.gov (United States)

    Chen, Ganchao; Fan, Junbing; Zhao, Tian; Xu, Xiaobo; Zhu, Mingqiang; Tang, Zhiyong

    2011-09-01

    Controlled synthesis of well-defined PbS nanostructures in terms of size and shape has been strongly motivated by their potential applications ranging from solar photovoltaics to near-infrared optics. Hereby, we report a facile microwave-assistant method for ultrafast fabrication of PbS nanostructures, by which uniform PbS hexapods with six arms stretching along six (100) directions of the crystal seeds have been easily synthesized within minutes. Various morphologies including rectangle plates, uniform cubes as well as nanoparticles were obtained by tuning the parameters for the formation of PbS nanocrystals. The results reveal that both concentration and feed ratio of precursors determine the growth of PbS nanocrystals significantly. And higher initial precursor concentration favors the formation of the hexapod structures. The process of crystal growth is monitored through scanning electron microscopy of PbS from different durations of the reaction. This controlled ultrafast synthesis of PbS structures at nanometer and micrometer scale with various morphologies may be promising in large scale fabrication of nanostructures. Based on the systematically study of the growth process, a possible mechanism for the formation of the hexapod-like structure is discussed.

  18. High-performance perovskite light-emitting diodes via morphological control of perovskite films.

    Science.gov (United States)

    Yu, Jae Choul; Kim, Da Bin; Jung, Eui Dae; Lee, Bo Ram; Song, Myoung Hoon

    2016-04-07

    Solution-processable perovskite materials have garnered tremendous attention because of their excellent charge carrier mobility, possibility of a tunable optical bandgap, and high photoluminescence quantum efficiency (PLQE). In particular, the uniform morphology of a perovskite film is the most important factor in realizing perovskite light-emitting diodes (PeLEDs) with high efficiency and full-coverage electroluminescence (EL). In this study, we demonstrate highly efficient PeLEDs that contain a perovskite film with a uniform morphology by introducing HBr into the perovskite precursor. The introduction of HBr into the perovskite precursor results in a perovskite film with a uniform, continuous morphology because the HBr increases the solubility of the inorganic component in the perovskite precursor and reduces the crystallization rate of the perovskite film upon spin-coating. Moreover, PeLEDs fabricated using perovskite films with a uniform, continuous morphology, which were deposited using 6 vol% HBr in a dimethylformamide (DMF)/hydrobromic acid (HBr) cosolvent, exhibited full coverage of the green EL emission. Finally, the optimized PeLEDs fabricated with perovskite films deposited using the DMF/HBr cosolvent exhibited a maximum luminance of 3490 cd m(-2) (at 4.3 V) and a luminous efficiency of 0.43 cd A(-1) (at 4.3 V).

  19. Manipulation and control of the interfacial polarization in organic light-emitting diodes by dipolar doping

    Science.gov (United States)

    Jäger, Lars; Schmidt, Tobias D.; Brütting, Wolfgang

    2016-09-01

    Most of the commonly used electron transporting materials in organic light-emitting diodes exhibit interfacial polarization resulting from partially aligned permanent dipole moments of the molecules. This property modifies the internal electric field distribution of the device and therefore enables an earlier flat band condition for the hole transporting side, leading to improved charge carrier injection. Recently, this phenomenon was studied with regard to different materials and degradation effects, however, so far the influence of dilution has not been investigated. In this paper we focus on dipolar doping of the hole transporting material 4,4-bis[N-(1-naphthyl)-N-phenylamino]-biphenyl (NPB) with the polar electron transporting material tris-(8-hydroxyquinolate) aluminum (Alq3). Impedance spectroscopy reveals that changes of the hole injection voltage do not scale in a simple linear fashion with the effective thickness of the doped layer. In fact, the measured interfacial polarization reaches a maximum value for a 1:1 blend. Taking the permanent dipole moment of Alq3 into account, an increasing degree of dipole alignment is found for decreasing Alq3 concentration. This observation can be explained by the competition between dipole-dipole interactions leading to dimerization and the driving force for vertical orientation of Alq3 dipoles at the surface of the NPB layer.

  20. Microwave metamaterials—from passive to digital and programmable controls of electromagnetic waves

    Science.gov (United States)

    Cui, Tie Jun

    2017-08-01

    Since 2004, my group at Southeast University has been carrying out research into microwave metamaterials, which are classified into three catagories: metamaterials based on the effective medium model, plasmonic metamaterials for spoof surface plasmon polaritons (SPPs), and coding and programmable metamaterials. For effective-medium metamaterials, we have developed a general theory to accurately describe effective permittivity and permeability in semi-analytical forms, from which we have designed and realized a three dimensional (3D) wideband ground-plane invisibility cloak, a free-space electrostatic invisibility cloak, an electromagnetic black hole, optical/radar illusions, and radially anisotropic zero-index metamaterial for omni-directional radiation and a nearly perfect power combination of source array, etc. We have also considered the engineering applications of microwave metamaterials, such as a broadband and low-loss 3D transformation-optics lens for wide-angle scanning, a 3D planar gradient-index lens for high-gain radiations, and a random metasurface for reducing radar cross sections. In the area of plasmonic metamaterials, we proposed an ultrathin, narrow, and flexible corrugated metallic strip to guide SPPs with a small bending loss and radiation loss, from which we designed and realized a series of SPP passive devices (e.g. power divider, coupler, filter, and resonator) and active devices (e.g. amplifier and duplexer). We also showed a significant feature of the ultrathin SPP waveguide in overcoming the challenge of signal integrity in traditional integrated circuits, which will help build a high-performance SPP wireless communication system. In the area of coding and programmable metamaterials, we proposed a new measure to describe a metamaterial from the viewpoint of information theory. We have illustrated theoretically and experimentally that coding metamaterials composed of digital units can be controlled by coding sequences, leading to different

  1. Fundamental Properties and Practical Application of Active Microwave Metamaterials Incorporating Gain Devices

    Science.gov (United States)

    2017-02-22

    person shall be subject to any penalty for failing to comply with a collection of information   if it does not display a currently valid OMB control... transmission line and an active volumetric metamaterial. These designs have been extended to THz frequency range. In addition, we have investigated the non...circuits,” IEEE International Microwave Symposium, Phoenix, Arizona, May 17-22, 2015. [7] Q. Tang, and H. Xin, “Stability of Tunnel Diode based Negative

  2. Design and development of an electrically-controlled beam steering mirror for microwave tomography

    Energy Technology Data Exchange (ETDEWEB)

    Tayebi, A., E-mail: tayebiam@msu.edu [Department of Electrical and Computer Engineering, College of Engineering, Michigan State University, East Lansing, MI 48824, USA and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Tang, J.; Paladhi, P. Roy; Udpa, L.; Udpa, S. [Department of Electrical and Computer Engineering, College of Engineering, Michigan State University, East Lansing, MI-48824, USA and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

    2015-03-31

    Microwave tomography has gained significant attention due to its reliability and unhazardous nature in the fields of NDE and medical industry. A new microwave tomography system is presented in this paper, which significantly reduces the design and operational complexities of traditional microwave imaging systems. The major component of the proposed system is a reconfigurable reflectarray antenna which is used for beam steering in order to generate projections from multiple angles. The design, modeling and fabrication of the building block of the antenna, a tunable unit cell, are discussed in this paper. The unit cell is capable of dynamically altering the phase of the reflected field which results in beam steering ability of the reflectarray antenna. A tomographically reconstructed image of a dielectric sample using this new microwave tomography system is presented in this work.

  3. Computer-Controlled Microwave Drying of Potentially Difficult Organic and Inorganic Soils

    Science.gov (United States)

    1990-12-01

    known to have a saturated, surface dry water content of about 3 percent and then subjecting the material to microwave drying. The gravels were...surface dry water content) of some coarse aggregate of chert, limestone, basalt, and quartz. Clay, at the other extreme, can exist at water contents...excluding such oversize particles from microwave water content specimens. c. The saturated surface dry water content of many rock or gravel particles has an

  4. Ultrafast control of nuclear spins using only microwave pulses: towards switchable solid-state quantum gates

    CERN Document Server

    Mitrikas, George; Papavassiliou, Georgios

    2009-01-01

    Since the idea of quantum information processing (QIP) fascinated the scientific community, electron and nuclear spins have been regarded as promising candidates for quantum bits (qubits). A fundamental challenge in the realization of a solid-state quantum computer is the construction of fast and reliable two-qubit quantum gates. Of particular interest in this direction are hybrid systems of electron and nuclear spins, where the two qubits are coupled through the hyperfine interaction. However, the significantly different gyromagnetic ratios of electron and nuclear spins do not allow for their coherent manipulation at the same time scale. Here we demonstrate the control of the alpha-proton nuclear spin, I=1/2, coupled to the stable radical CH(COOH)2, S=1/2, in a gamma-irradiated malonic acid single crystal using only microwave pulses. We show that, depending on the state of the electron spin (mS=+1/2 or -1/2), the nuclear spin can be locked in a desired state or oscillate between mI=+1/2 and mI=-1/2 on the na...

  5. Mode locking and spatiotemporal chaos in periodically driven Gunn diodes

    DEFF Research Database (Denmark)

    Mosekilde, Erik; Feldberg, Rasmus; Knudsen, Carsten;

    1990-01-01

    Numerical simulation is applied to study the highly nonlinear-dynamic phenomena that can arise in Gunn diodes by interaction between the internally generated domain mode and an external microwave signal. By adjusting the time of domain formation and the speed of propagation, the internal...... oscillation entrains with the external signal. This produces a devil’s staircase of frequency-locked solutions. At higher microwave amplitudes, period doubling and other forms of mode-converting bifurcations can be seen. In this interval the diode also exhibits spatiotemporal chaos. At still higher microwave...

  6. Microwave engineering

    CERN Document Server

    Pozar, David M

    2012-01-01

    The 4th edition of this classic text provides a thorough coverage of RF and microwave engineering concepts, starting from fundamental principles of electrical engineering, with applications to microwave circuits and devices of practical importance.  Coverage includes microwave network analysis, impedance matching, directional couplers and hybrids, microwave filters, ferrite devices, noise, nonlinear effects, and the design of microwave oscillators, amplifiers, and mixers. Material on microwave and RF systems includes wireless communications, radar, radiometry, and radiation hazards. A large

  7. A novel solution for car traffic control based on radiometric microwave devices

    Science.gov (United States)

    Soldovieri, Francesco; Denisov, Alexander; Speziale, Victor

    2014-05-01

    The significant problem of traffic in big cities, connected with huge and building up quantity of automobile cars, demands for novel strategies, based on nonconventional solutions, in order to improve system traffic control, especially at crossroads. As well known, the usual solution is based on the time relay, which requires the installation of a fixed traffic interval (signal light switching) at a crossroad; this solution is low cost, but does not account for the actual traffic conditions. Therefore, in the recent years, attention is towards to new designs, where the monitoring of the and control of traffic is carried out by using various methods including, optical, the infrared, magnetic, radar tracking, acoustical ones. In this work, we discuss the deployment of high sensitivity radiometric systems and radiometers(sensor) in the microwave range [1, 2]. In fact, the radiometer as "sensor" can provide an always updated information about the car traffic in any weather condition and in absence or low visibility conditions. In fact, the radiometric sensor detects the cars thanks to the different behavior of the car roofs which reflect the cold sky whereas the road asphalt is visible as warm object (at around outside temperature). [1] A. G. Denisov, V. P. Gorishnyak, S. E. Kuzmin et al., "Some experiments concerning resolution of 32 sensors passive 8mm wave imaging system," in Proceedings of the International Symposium on Space Terahertz Technology (ISSTT '09), Charlottesville, Va, USA, April 2009. [2] F. Soldovieri, A. Natale, V. Gorishnyak, A. Pavluchenko, A. Denisov, and L. Chen, "Radiometric Imaging for Monitoring and Surveillance Issues," International Journal of Antennas and Propagation, vol. 2013, Article ID 272561, 8 pages, 2013. doi:10.1155/2013/272561.

  8. Self-adaptive PID controller of microwave drying rotary device tuning on-line by genetic algorithms

    Institute of Scientific and Technical Information of China (English)

    杨彪; 梁贵安; 彭金辉; 郭胜惠; 李玮; 张世敏; 李英伟; 白松

    2013-01-01

    The control design, based on self-adaptive PID with genetic algorithms(GA) tuning on-line was investigated, for the temperature control of industrial microwave drying rotary device with the multi-layer(IMDRDWM) and with multivariable nonlinear interaction of microwave and materials. The conventional PID control strategy incorporated with optimization GA was put forward to maintain the optimum drying temperature in order to keep the moisture content below 1%, whose adaptation ability included the cost function of optimization GA according to the output change. Simulations on five different industrial process models and practical temperature process control system for selenium-enriched slag drying intensively by using IMDRDWM were carried out systematically, indicating the reliability and effectiveness of control design. The parameters of proposed control design are all on-line implemented without iterative predictive calculations, and the closed-loop system stability is guaranteed, which makes the developed scheme simpler in its synthesis and application, providing the practical guidelines for the control implementation and the parameter design.

  9. Tunable resonance cavity control in a near-field scanning microwave microscope

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Hyuk; Kim, Joo Young; Lee, Kre Jin [Sogang Univ., Seoul (Korea, Republic of); Kim, Jin Tae [KRISS, Daejon (Korea, Republic of); Cha, Deok Joon [Kunsan National Univ., Kunsan (Korea, Republic of); Lee, Yong San [Daejin Univ., Pochon (Korea, Republic of)

    2002-05-01

    We report a microwave surface imaging technique using a near-field scanning microwave microscope with a tunable resonance cavity. By tuning the resonance cavity, we could demonstrate improved sensitivity and spatial resolution of the near-field image of YBa{sub 2}Cu{sub 3}O{sub y} thin films on MgO substrates. By measuring the shift in the resonant frequency and the change in the quality factor, we obtained near-field scanning microwave images with a spatial resolution better than 4 {mu}m at an operating frequency of f=1-1.5 GHz. The principal of operation can be explained by using the perturbation theory of a coaxial resonant cavity, considering the radius of the probe tip and the sample-tip distance.

  10. A Solid-State Sub-Nanosecond Microwave Switch

    Science.gov (United States)

    Avdochenko, B. I.; Prudaev, I. A.; Tolbanov, O. P.; Chumerin, P. Yu.; Yurchenko, V. I.

    2016-12-01

    A problem is discussed of the microwave generator power switching with the use of high-speed subnanosecond avalanche diodes. A scheme of the measurement setup, a photo of the switch design, and the results of experimental studies are presented.

  11. Microwave Ovens

    Science.gov (United States)

    ... ovens heat food using microwaves, a form of electromagnetic radiation similar to radio waves. Microwaves have three characteristics ... that their microwave oven products meet the strict radiation safety standard ... if your microwave oven has damage to its door hinges, latches, or seals, or ...

  12. Rapid phase-controlled microwave synthesis of nanostructured hierarchical tetragonal and cubic β-In 2S 3 dandelion flowers

    Science.gov (United States)

    Naik, S. D.; Jagadale, T. C.; Apte, S. K.; Sonawane, R. S.; Kulkarni, M. V.; Patil, S. I.; Ogale, S. B.; Kale, B. B.

    2008-02-01

    Phase controlled synthesis of hierarchical nanostructured β-In 2S 3 dandelion flowers is realized by a rapid microwave solvothermal process using indium metal, nitric acid and thiourea as precursors. The tetragonal and cubic phases of the compound have been successfully and separately stabilized in the same type of dandelion morphology by using aqueous-mediated and methanol-mediated synthesis, respectively. The possible mechanism responsible for phase control is discussed. Optical properties of the flowers as well as their hydrogen generation capability by photodecomposition of H 2S under visible light are also reported.

  13. Development of constant-power driving control for light-emitting-diode (LED) luminaire

    KAUST Repository

    Huang, Bin-Juine

    2013-01-01

    The illumination of an LED may be affected by operating temperature even under constant-current condition. A constant-power driving technique is proposed in the present study for LED luminaire. A linear system dynamics model of LED luminaire is first derived and used in the design of the feedback control system. The PI controller was designed and tuned taking into account the control accuracy and robust properties with respect to plant uncertainty and variation of operating conditions. The control system was implemented on a microprocessor and used to control a 150W LED luminaire. The test result shows that the feedback system accurately controls the input power of LED luminaire to within 1.3 per cent error. As the ambient temperature changes from 0 to 40 °C, the LED illumination varies slightly (-1.7%) for constant-power driving, as compared to that of constant-current driving (-12%) and constant-voltage driving (+50%). The constant-power driving has revealed advantage in stabilizing the illumination of LED under large temperature variation. © 2012 Elsevier Ltd. All rights reserved.

  14. Monolithic millimeter-wave diode array beam controllers: Theory and experiment

    Science.gov (United States)

    Sjogren, L. B.; Liu, H.-X. L.; Wang, F.; Liu, T.; Wu, W.; Qin, X.-H.; Chung, E.; Domier, C. W.; Luhmann, N. C., Jr.; Maserjian, J.

    1992-01-01

    In the current work, multi-function beam control arrays have been fabricated and have successfully demonstrated amplitude control of transmitted beams in the W and D bands (75-170 GHz). While these arrays are designed to provide beam control under DC bias operation, new designs for high-speed electronic and optical control are under development. These arrays will fill a need for high-speed watt-level beam switches in pulsed reflectometer systems under development for magnetic fusion plasma diagnostics. A second experimental accomplishment of the current work is the demonstration in the 100-170 GHz (D band) frequency range of a new technique for the measurement of the transmission phase as well as amplitude. Transmission data can serve as a means to extract ('de-embed') the grid parameters; phase information provides more complete data to assist in this process. Additional functions of the array beam controller yet to be tested include electronically controlled steering and focusing of a reflected beam. These have application in the areas of millimeter-wave electronic scanning radar and reflectometry, respectively.

  15. Microwave imaging

    CERN Document Server

    Pastorino, Matteo

    2010-01-01

    An introduction to the most relevant theoretical and algorithmic aspects of modern microwave imaging approaches Microwave imaging-a technique used in sensing a given scene by means of interrogating microwaves-has recently proven its usefulness in providing excellent diagnostic capabilities in several areas, including civil and industrial engineering, nondestructive testing and evaluation, geophysical prospecting, and biomedical engineering. Microwave Imaging offers comprehensive descriptions of the most important techniques so far proposed for short-range microwave imaging-in

  16. Solid phase synthesis of fatty acid modified glucagon-like peptide-1(7-36) amide under thermal and controlled microwave irradiation

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Fatty acid modified glucagon-like peptide-1(7-36) amide was synthesized efficiently on Rink-Amide-MBHA resin by microwave-assisted solid phase method.The method of thermal and controlled microwave irradiation provided impressive enhancements in product yield,selectivity,and reaction rate.The coupling time was dramatically decreased to 6 min,and the desired products were obtained in high yield and purity.

  17. Microwave control using a high-gain bias-free optoelectronic switch

    Science.gov (United States)

    Freeman, J. L.; Ray, S.; West, D. L.; Thompson, A. G.; Lagasse, M. J.

    1991-08-01

    We describe an optoelectronic microwave switch that exploits the high optical sensitivity of the air-GaAs interface. With an optical power of 100 micro-W, the switch has an insertion loss of 3.4 dB and an isolation of greater than 20 dB from 0 to 10 GHz. No electrical power is needed.

  18. Expeditious organic–free assembly: morphologically controlled synthesis of iron oxides using microwaves

    Science.gov (United States)

    A microwave hydrothermal method is developed for the synthesis of iron oxides, α-Fe2O3, β-FeOOH, and the junction of α-Fe2O3–β-FeOOH. This method is absolutely organic-free, and various structures could be obtained simply by changing th...

  19. High-fidelity spatial addressing of 43Ca+ qubits using near-field microwave control

    Science.gov (United States)

    Prado Lopes Aude Craik, Diana; Linke, Norbert; Allcock, David; Sepiol, Martin; Harty, Thomas; Ballance, Christopher; Stacey, Derek; Steane, Andrew; Lucas, David

    2016-05-01

    Individual addressing of qubits is essential for scalable quantum computation. Spatial addressing allows unlimited numbers of qubits to share the same frequency, whilst enabling arbitrary parallel operations. We present the latest experimental results obtained using a two-zone microfabricated surface trap designed to perform spatial, near-field microwave addressing of long-lived 43Ca+ ``atomic clock'' qubits held in separate trap zones (each of which feature four integrated microwave electrodes). Microwave near fields generated by multi-electrode chip ion traps are often difficult to faithfully simulate and a simple method of characterizing and testing trap chips before placement under ultra-high vacuum would significantly speed up trap design optimization. We describe a printed circuit board antenna for use in mapping microwave near-fields generated by ion-trap electrodes. The antenna is designed to measure fields down to 100 μ m away from trap electrodes and to be impedance matched at a desired spot frequency for an improved signal to noise ratio in field measurements. This work is supported by the US Army Research Office, EPSRC (UK) and the UK National Quantum Technologies Programme.

  20. Expeditious organic–free assembly: morphologically controlled synthesis of iron oxides using microwaves

    Science.gov (United States)

    A microwave hydrothermal method is developed for the synthesis of iron oxides, α-Fe2O3, β-FeOOH, and the junction of α-Fe2O3–β-FeOOH. This method is absolutely organic-free, and various structures could be obtained simply by changing th...

  1. Plant lighting system with five wavelength-band light-emitting diodes providing photon flux density and mixing ratio control

    Directory of Open Access Journals (Sweden)

    Yano Akira

    2012-11-01

    Full Text Available Abstract Background Plant growth and development depend on the availability of light. Lighting systems therefore play crucial roles in plant studies. Recent advancements of light-emitting diode (LED technologies provide abundant opportunities to study various plant light responses. The LED merits include solidity, longevity, small element volume, radiant flux controllability, and monochromaticity. To apply these merits in plant light response studies, a lighting system must provide precisely controlled light spectra that are useful for inducing various plant responses. Results We have developed a plant lighting system that irradiated a 0.18 m2 area with a highly uniform distribution of photon flux density (PFD. The average photosynthetic PFD (PPFD in the irradiated area was 438 micro-mol m–2 s–1 (coefficient of variation 9.6%, which is appropriate for growing leafy vegetables. The irradiated light includes violet, blue, orange-red, red, and far-red wavelength bands created by LEDs of five types. The PFD and mixing ratio of the five wavelength-band lights are controllable using a computer and drive circuits. The phototropic response of oat coleoptiles was investigated to evaluate plant sensitivity to the light control quality of the lighting system. Oat coleoptiles irradiated for 23 h with a uniformly distributed spectral PFD (SPFD of 1 micro-mol m–2 s–1 nm–1 at every peak wavelength (405, 460, 630, 660, and 735 nm grew almost straight upwards. When they were irradiated with an SPFD gradient of blue light (460 nm peak wavelength, the coleoptiles showed a phototropic curvature in the direction of the greater SPFD of blue light. The greater SPFD gradient induced the greater curvature of coleoptiles. The relation between the phototropic curvature (deg and the blue-light SPFD gradient (micro-mol m–2 s–1 nm–1 m–1 was 2 deg per 1 micro-mol m–2 s–1 nm–1 m–1. Conclusions The plant lighting system, with a computer with a

  2. Carrier-Based Common Mode Voltage Control Techniques in Three-Level Diode-Clamped Inverter

    Directory of Open Access Journals (Sweden)

    Pradyumn Chaturvedi

    2012-01-01

    Full Text Available Switching converters are used in electric drive applications to produce variable voltage, variable frequency supply which generates harmful large dv/dt and high-frequency common mode voltages (CMV. Multilevel inverters generate lower CMV as compared to conventional two-level inverters. This paper presents simple carrier-based technique to control the common mode voltages in multilevel inverters using different structures of sine-triangle comparison method such as phase disposition (PD, phase opposition disposition (POD by adding common mode voltage offset signal to actual reference voltage signal. This paper also presented the method to optimize the magnitude of this offset signal to reduce CMV and total harmonic distortion in inverter output voltage. The presented techniques give comparable performance as obtained in complex space vector-based control strategy, in terms of number of commutations, magnitude, and rate of change of CMV and harmonic profile of inverter output voltage. Simulation and experimental results presented confirm the effectiveness of the proposed techniques to control the common mode voltages.

  3. Analysis and Design of Phase Change Thermal Control for Light Emitting Diode (LED) Spacesuit Helmet Lights

    Science.gov (United States)

    Bue, Grant C.; Nguyen, Hiep X.; Keller, John R.

    2010-01-01

    LED Helmet Extravehicular Activity Helmet Interchangeable Portable (LEHIP) lights for the Extravehicular Mobility Unit (EMU) have been built and tested and are currently being used on the International Space Station. A design is presented of the passive thermal control system consisting of a chamber filled with aluminum foam and wax. A thermal math model of LEHIP was built and correlated by test to show that the thermal design maintains electronic components within hot and cold limits for a 7 hour spacewalk in the most extreme EVA average environments, and do not pose a hazard to the crew or to components of the EMU.

  4. Characterization of a digital microwave radiometry system for noninvasive thermometry using a temperature-controlled homogeneous test load.

    Science.gov (United States)

    Arunachalam, K; Stauffer, P R; Maccarini, P F; Jacobsen, S; Sterzer, F

    2008-07-21

    Microwave radiometry has been proposed as a viable noninvasive thermometry approach for monitoring subsurface tissue temperatures and potentially controlling power levels of multielement heat applicators during clinical hyperthermia treatments. With the evolution of technology, several analog microwave radiometry devices have been developed for biomedical applications. In this paper, we describe a digital microwave radiometer with built-in electronics for signal processing and automatic self-calibration. The performance of the radiometer with an Archimedean spiral receive antenna is evaluated over a bandwidth of 3.7-4.2 GHz in homogeneous and layered water test loads. Controlled laboratory experiments over the range of 30-50 degrees C characterize measurement accuracy, stability, repeatability and penetration depth sensitivity. The ability to sense load temperature through an intervening water coupling bolus of 6 mm thickness is also investigated. To assess the clinical utility and sensitivity to electromagnetic interference (EMI), experiments are conducted inside standard clinical hyperthermia treatment rooms with no EM shielding. The digital radiometer provided repeatable measurements with 0.075 degrees C resolution and standard deviation of 0.217 degrees C for homogeneous and layered tissue loads at temperatures between 32-45 degrees C. Within the 3.7-4.2 GHz band, EM noise rejection was good other than some interference from overhead fluorescent lights in the same room as the radiometer. The system response obtained for ideal water loads suggests that this digital radiometer should be useful for estimating subcutaneous tissue temperatures under a 6 mm waterbolus used during clinical hyperthermia treatments. The accuracy and stability data obtained in water test loads of several configurations support our expectation that single band radiometry should be sufficient for sub-surface temperature monitoring and power control of large multielement array superficial

  5. Characterization of a digital microwave radiometry system for noninvasive thermometry using a temperature-controlled homogeneous test load

    Energy Technology Data Exchange (ETDEWEB)

    Arunachalam, K; Stauffer, P R; Maccarini, P F [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Jacobsen, S [Department of Physics and Technology, University of Tromso, N-9037 (Norway); Sterzer, F [MMTC, Inc. Princeton, NJ 08540 (United States)], E-mail: kavitha.arunachalam@duke.edu

    2008-07-21

    Microwave radiometry has been proposed as a viable noninvasive thermometry approach for monitoring subsurface tissue temperatures and potentially controlling power levels of multielement heat applicators during clinical hyperthermia treatments. With the evolution of technology, several analog microwave radiometry devices have been developed for biomedical applications. In this paper, we describe a digital microwave radiometer with built-in electronics for signal processing and automatic self-calibration. The performance of the radiometer with an Archimedean spiral receive antenna is evaluated over a bandwidth of 3.7-4.2 GHz in homogeneous and layered water test loads. Controlled laboratory experiments over the range of 30-50 deg. C characterize measurement accuracy, stability, repeatability and penetration depth sensitivity. The ability to sense load temperature through an intervening water coupling bolus of 6 mm thickness is also investigated. To assess the clinical utility and sensitivity to electromagnetic interference (EMI), experiments are conducted inside standard clinical hyperthermia treatment rooms with no EM shielding. The digital radiometer provided repeatable measurements with 0.075 deg. C resolution and standard deviation of 0.217 deg. C for homogeneous and layered tissue loads at temperatures between 32-45 deg. C. Within the 3.7-4.2 GHz band, EM noise rejection was good other than some interference from overhead fluorescent lights in the same room as the radiometer. The system response obtained for ideal water loads suggests that this digital radiometer should be useful for estimating subcutaneous tissue temperatures under a 6 mm waterbolus used during clinical hyperthermia treatments. The accuracy and stability data obtained in water test loads of several configurations support our expectation that single band radiometry should be sufficient for sub-surface temperature monitoring and power control of large multielement array superficial hyperthermia

  6. Characterization of a digital microwave radiometry system for noninvasive thermometry using a temperature-controlled homogeneous test load

    Science.gov (United States)

    Arunachalam, K.; Stauffer, P. R.; Maccarini, P. F.; Jacobsen, S.; Sterzer, F.

    2008-07-01

    Microwave radiometry has been proposed as a viable noninvasive thermometry approach for monitoring subsurface tissue temperatures and potentially controlling power levels of multielement heat applicators during clinical hyperthermia treatments. With the evolution of technology, several analog microwave radiometry devices have been developed for biomedical applications. In this paper, we describe a digital microwave radiometer with built-in electronics for signal processing and automatic self-calibration. The performance of the radiometer with an Archimedean spiral receive antenna is evaluated over a bandwidth of 3.7-4.2 GHz in homogeneous and layered water test loads. Controlled laboratory experiments over the range of 30-50 °C characterize measurement accuracy, stability, repeatability and penetration depth sensitivity. The ability to sense load temperature through an intervening water coupling bolus of 6 mm thickness is also investigated. To assess the clinical utility and sensitivity to electromagnetic interference (EMI), experiments are conducted inside standard clinical hyperthermia treatment rooms with no EM shielding. The digital radiometer provided repeatable measurements with 0.075 °C resolution and standard deviation of 0.217 °C for homogeneous and layered tissue loads at temperatures between 32-45 °C. Within the 3.7-4.2 GHz band, EM noise rejection was good other than some interference from overhead fluorescent lights in the same room as the radiometer. The system response obtained for ideal water loads suggests that this digital radiometer should be useful for estimating subcutaneous tissue temperatures under a 6 mm waterbolus used during clinical hyperthermia treatments. The accuracy and stability data obtained in water test loads of several configurations support our expectation that single band radiometry should be sufficient for sub-surface temperature monitoring and power control of large multielement array superficial hyperthermia applicators.

  7. Advanced Microwave Ferrite Research (AMFeR): Phase Two

    Science.gov (United States)

    2006-12-31

    sources, such as a klystron or a Gunn diode . The waveguide system involves two coax-to-waveguide adaptors, a directional coupler, a waveguide short...or Gunn Diode » Microwave Source Isolator HP8350B Sweeper> upto 20 Ghz waveguide 1 Directional to Type N Coupler Coax Adator < Scalar Netw~ork...two isolators, one standard un-calibrated diode detector, and one calibrated detector for the network analyzer. The magnetic sample is mounted on the

  8. Controlled silver delivery by silver-cellulose nanocomposites prepared by a one-pot green synthesis assisted by microwaves

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Ana Rosa; Unali, Gianfranco, E-mail: ana.rosa.silva@ua.pt [Structured Materials Expertise Group, Unilever Discover Port Sunlight, Quarry Road East, Bebington CH63 3JW (United Kingdom)

    2011-08-05

    Controlled silver release from cellulosic nanocomposites was achieved by synthesizing silver nanoparticles, under microwave heating for 1-15 min, in a one-pot, versatile and sustainable process in which microcrystalline cellulose simultaneously functions as reducing, stabilizing and supporting agent in water; chitin, starch and other cellulose derivatives could also be used as reducing, stabilizing and supporting agents for silver nanoparticles and the method was also found to be extensible to the preparation of noble metal (Au, Pt) and metal oxide nanoparticle (ZnO, Cu, CuO and Cu{sub 2}O) nanocomposites.

  9. Facile synthesis of Ni/ZnO composite: Morphology control and microwave absorption properties

    Science.gov (United States)

    Zhao, Biao; Shao, Gang; Fan, Bingbing; Guo, Wenhui; Xie, Yajun; Zhang, Rui

    2015-05-01

    In this work, Ni/ZnO composites with varying morphologies were synthesized by a facile hydrothermal method. X-ray diffraction (XRD) and Scanning electron microscopy (SEM) were performed to characterize Ni/ZnO composites. SEM images reveal that NH3·H2O concentration play a vital role on morphology of Ni/ZnO composite. The complex permittivity and permeability of three different morphologies of Ni/ZnO were measured in the frequency range of 1-18 GHz and their microwave absorption properties were investigated. The core-shell structured Ni/ZnO (ZnO polyhedron coating) composite prepared for 1.0 mL NH3·H2O shows excellent microwave absorption properties. A minimum reflection loss is -48.6 dB at 13.4 GHz and the corresponding thickness is 2.0 mm. The effective absorption (below -10 dB) can be tuned between 9.0 GHz and 18.0 GHz by adjusting thickness in 1.5-2.5 mm, and the frequency for RL exceeding -20 dB is located at 11.1-16.2 GHz with thickness of 1.8-2.2 mm. It is demonstrated that the polyhedron ZnO-coated Ni composite is a promising microwave absorbent with small thickness, strong absorption, and broad bandwidth.

  10. Enhanced Emission Efficiency of Size-Controlled InGaN/GaN Green Nanopillar Light-Emitting Diodes

    DEFF Research Database (Denmark)

    Ou, Yiyu; Iida, Daisuke; Fadil, Ahmed

    2016-01-01

    Nanopillar InGaN/GaN green light-emitting diode (LED) arrays were fabricated by self-assembled Au nanoparticles patterning and dry etching process. Structure size and density of the nanopillar arrays have been modified by varying the Au film thickness in the nanopatterning process. Fabricated...

  11. Microwave Photonics

    OpenAIRE

    Seeds, A.J.; Liu, C. P.; T. Ismail; Fice, M. J.; Pozzi, F; Steed, R. J.; Rouvalis, E.; Renaud, C.C.

    2010-01-01

    Microwave photonics is the use of photonic techniques for the generation, transmission, processing and reception of signals having spectral components at microwave frequencies. This tutorial reviews the technologies used and gives applications examples.

  12. Dynamic Antenna Alignment Control in Microwave Air-Bridging for Sky-Net Mobile Communication Using Unmanned Flying Platform

    Directory of Open Access Journals (Sweden)

    Chin E. Lin

    2015-01-01

    Full Text Available This paper presents a preliminary study on establishing a mobile point-to-point (P2P microwave air-bridging (MAB between Unmanned Low Altitude Flying Platform (ULAFP and backhaul telecommunication network. The proposed Sky-Net system relays telecom signal for general mobile cellphone users via ULAFP when natural disaster sweeps off Base Transceiver Stations (BTSs. Unlike the conventional fix point microwave bridging application, the ULAFP is cruising on a predefined mission flight path to cover a wider range of service. The difficulty and challenge fall on how to maintain antenna alignment accurately in order to provide the signal strength for MAB. A dual-axis rotation mechanism with embedded controller is designed and implemented on airborne and ground units for stabilizing airborne antenna and tracking the moving ULAFP. The MAB link is established in flight tests using the proposed antenna stabilizing/tracking mechanism with correlated control method. The result supports backbone technique of the Sky-Net mobile communication and verifies the feasibility of airborne e-Cell BTS.

  13. The study of disk resonators diode modules, solid-state generators active

    Directory of Open Access Journals (Sweden)

    B. A. Kotserzhinskii

    1987-12-01

    Full Text Available The results of an experimental study of disk resonators diode modules, solid-state active microwave generators. The effect of current leads, as well as errors in the manufacture of resonators their characteristics.

  14. Bias field free tunability of microwave properties based on geometrically controlled isolated permalloy nanomagnets

    Science.gov (United States)

    Haldar, Arabinda; Adeyeye, Adekunle Olusola

    2016-04-01

    We have investigated the static and dynamic properties of two lithographically patterned bi-stable nanomagnets. Different ground magnetic states were realized using a simple in-plane field initialization technique. These states were directly imaged with magnetic force microscopy. Using the broadband ferromagnetic spectroscopy, we show that different magnetic ground states are associated with distinct microwave absorption spectra due to the variation of the internal magnetic field leading to large shift between the absorption spectra. Our experimental observations are in good agreement with micromagnetic simulations which also indicate the possibility of sub-ns switching between magnetic states using a rectangular pulse field.

  15. Dynamic metamaterial aperture for microwave imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sleasman, Timothy; Imani, Mohammadreza F.; Gollub, Jonah N.; Smith, David R. [Center for Metamaterials and Integrated Plasmonics, Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina, 27708 (United States)

    2015-11-16

    We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The aperture consists of an array of complementary, resonant metamaterial elements patterned into the upper conductor of a microstrip line. Each metamaterial element contains two diodes connected to an external control circuit such that the resonance of the metamaterial element can be damped by application of a bias voltage. Through applying different voltages to the control circuit, select subsets of the elements can be switched on to create unique radiation patterns that illuminate the scene. Spatial information of an imaging domain can thus be encoded onto this set of radiation patterns, or measurements, which can be processed to reconstruct the targets in the scene using compressive sensing algorithms. We discuss the design and operation of a metamaterial imaging system and demonstrate reconstructed images with a 10:1 compression ratio. Dynamic metamaterial apertures can potentially be of benefit in microwave or millimeter wave systems such as those used in security screening and through-wall imaging. In addition, feature-specific or adaptive imaging can be facilitated through the use of the dynamic aperture.

  16. Microwave Semiconductor Research - Materials, Devices, Circuits.

    Science.gov (United States)

    1981-12-01

    34, M.S. Thesis, Cornell University, Ithaca, NY, May 1978. 2. Richard A. Hackborn, "An Automatic Network Analyzer System", Microwave Journal, Vol. 11, No. 5...Circuit Determination of Gunn Diodes", IEEE Trans. on Microwave Thy. and Tech., Vol. MTT-18, No. 11, pp. 784-790, Nov. 1970. 6. J. W. Bandler , "Precision...34, IEEE Trans. on Microwave Thy. and Tech., Vol. MTT-22, No. 7, pp. 709-718, July 1974. 9. Paul T. Greiling, Richard W. Lanton, "Determination of

  17. Microwave method for synthesis of micro- and nanostructures with controllable composition during gyrotron discharge

    Science.gov (United States)

    Batanov, German M.; Borzosekov, Valentin D.; Golberg, Dmitri; Iskhakova, Ludmila D.; Kolik, Leonid V.; Konchekov, Evgeny M.; Kharchev, Nikolai K.; Letunov, Alexander A.; Malakhov, Dmitry V.; Milovich, Filipp O.; Obraztsova, Ekaterina A.; Petrov, Alexander E.; Ryabikina, Irina G.; Sarksian, Karen A.; Stepakhin, Vladimir D.; Skvortsova, Nina N.

    2016-01-01

    We introduce an approach toward the synthesis of micro- and nanostructures under nonequilibrium microwave discharges within metal-dielectric powder mixtures induced by powerful microwave gyrotron radiation. A new plasma-chemical reactor capable of sustaining a discharge regime with an afterglow phase of an order of magnitude longer than the gyrotron pulse duration was constructed for these experiments. In the nonequilibrium conditions of such a discharge, plasma-induced exothermic chemical reactions leading to the synthesis of various compounds were initiated. The synthesized structures were deposited on the reactor walls and on the impurity particles within the reactor. This method was tested under gyrotron-initiated discharges within various metal-dielectric powder mixtures of titanium-boron, molybdenum-boron, titanium-silicon-boron, molybdenum-boron nitride, molybdenum-tungsten-boron nitride, and so on. Depending on the powder mixture composition, reactor atmosphere, and other parameters, micro- and nanosized particles of boron nitride, titanium diboride, molybdenum boride, titanium boride, molybdenum, and molybdenum oxide, were synthesized, detected, and analyzed.

  18. Production of electron cyclotron resonance plasma by using multifrequencies microwaves and active beam profile control on a large bore electron cyclotron resonance ion source with permanent magnets.

    Science.gov (United States)

    Kato, Yushi; Watanabe, Takeyoshi; Matsui, Yuuki; Hirai, Yoshiaki; Kutsumi, Osamu; Sakamoto, Naoki; Sato, Fuminobu; Iida, Toshiyuki

    2010-02-01

    A new concept on magnetic field with all magnets on plasma production and confinement has been proposed to enhance efficiency of an electron cyclotron resonance (ECR) plasma for broad and dense ion beam source under the low pressure. The magnetic field configuration is constructed by a pair of magnets assembly, i.e., comb-shaped magnet which cylindrically surrounds the plasma chamber. The resonance zones corresponding to the fundamental ECR for 2.45 GHz and 11-13 GHz frequencies are constructed at different positions. The profiles of the plasma parameters in the ECR ion source are different from each frequency of microwave. Large bore extractor is set at the opposite side against the microwave feeds. It is found that differences of their profiles also appear at those of ion beam profiles. We conducted to launch simultaneously multiplex frequencies microwaves controlled individually, and tried to control the profiles of the plasma parameters and then those of extracted ion beam.

  19. Intensity noise in diode-pumped single-frequency Nd:YAG lasers and its control by electronic feedback

    Science.gov (United States)

    Kane, Thomas J.

    1990-01-01

    The power spectrum of the relative intensity noise (RIN) of single-frequency diode-pumped Nd:YAG lasers is observed to be shot-noise limited at frequencies above 20 MHz for a photocurrent of up to 4.4 mA. Relaxation oscillations result in noise 60-70 dB above shot noise at a few hundred kHz. These relaxation oscillations have been suppressed using electronic feedback.

  20. Mechanism analysis of radiation generated by the beam-plasma interaction in a vacuum diode

    Science.gov (United States)

    Zengchao, Ji; Shixiu, Chen; Shen, Gao

    2017-01-01

    When we were studying the vacuum switch, we found that the vacuum diode can radiate a broadband microwave. The vacuum diode is comprised of a cathode with a trigger device and planar anode, there is not a metallic bellows waveguide structure in this device, so the radiation mechanism of the vacuum diode is different from the plasma filled microwave device. It is hard to completely imitate the theory of the plasma filled microwave device. This paper analyzes the breakdown process of the vacuum diode, establishes the mathematical model of the radiating microwave from the vacuum diode. Based on the analysis of the dispersion relation in the form of a refractive index, the electromagnetic waves generated in the vacuum diode will resonate. The included angle between the direction of the electromagnetic radiation and the initial motion direction of electron beam is 45 degrees. The paper isolates the electrostatic effect from the beam-plasma interaction when the electromagnetic radiation occurs. According to above analyses, the dispersion relations of radiation are obtained by solving the wave equation. The dispersion curves are also obtained based on the theoretical dispersion relations. The theoretical dispersion curves are consistent with the actual measurement time-frequency maps of the radiation. Theoretical deduction and experiments indicate that the reason for microwave radiating from the vacuum diode can be well explained by the interaction of the electron beam and magnetized plasma. Supported by National Nature Science Foundation of China (No. 11075123), the Young Scientists Fund of Nature Science Foundation of China (No. 51207171).

  1. A PIN diode controlled dual-tuned MRI RF coil and phased array for multi nuclear imaging

    Science.gov (United States)

    Ha, Seunghoon; Hamamura, Mark J.; Nalcioglu, Orhan; Tugan Muftuler, L.

    2010-05-01

    MR imaging of nuclei other than hydrogen has been used to investigate metabolism in humans and animals. However, MRI observable nuclei other than hydrogen are not as abundant and as a result the image SNR is lower. Dual-tuned radio frequency (RF) coils are developed for these studies in which high-resolution structural images are acquired using hydrogen and metabolic information is acquired by exciting the other nucleus. Using a dual-tuned coil, the experimenter avoids the inconvenience of moving the patient out and replacing the RF coil for imaging different nuclei. This also eliminates image registration problems. However, the common scheme of using trap circuits for dual-tuned operation results in increased coil losses as well as problems in obtaining optimal tuning and matching at both frequencies. Here, a new approach is presented using PIN diodes to switch the coil between two resonance frequencies. This design eliminates the need for the trap circuit and associated losses from the self-resistance of the trap circuit inductors. At the operating frequencies we used, the equivalent series resistance of an inductor is higher than that of the PIN diodes. In order to test the efficacy of this new approach, we first built two surface coils of identical geometry, one with the conventional trap circuits and one with the PIN diode switches. We also studied the performances of both coils when the coils are divided into shorter conductors segments by adding more tuning elements. It is known that dividing the coil into shorter conductor segments helps reduce radiation and electric field losses. We explored this effect for both coils at both operating frequencies. Finally, a dual-tuned receive-only phased array was designed and built with the PIN diode circuit to switch between two resonance frequencies. A conventional dual-tuned birdcage coil was designed and built to transmit RF power. A unique feature of this coil is that the RF power is fed through two separate sets

  2. A study on morphology control and optical properties of ZnO nanorods synthesized by microwave heating

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, M.K.; Huang, C.C. [Department of Electronic Engineering and Research Center for Micro/Nano Technology, Tungnan University, Taipei, Taiwan (China); Lee, Y.C., E-mail: jacklee@mail.tnu.edu.tw [Department of Electronic Engineering and Research Center for Micro/Nano Technology, Tungnan University, Taipei, Taiwan (China); Yang, C.S.; Yu, H.C. [Graduate Institute of Electro-optical Engineering, Tatung University, Taipei, Taiwan (China); Lee, J.W. [Department of Materials Engineering, Ming Chi University of Technology, Taipei, Taiwan (China); Hu, S.Y. [Department of Electrical Engineering, Tung Fang Design University, Kaohsiung, Taiwan (China); Chen, C.H. [Protrustech Corporation Limited, Tainan, Taiwan (China)

    2012-01-15

    In this study, we present morphology control investigations on zinc oxide (ZnO) nanorods synthesized by microwave heating of a mixture of zinc nitrate hexahydrate and hexamethylenetetramine (HMTA) precursors in deionized water (DI water). To study the morphology and structural variations of the obtained ZnO nanorods in different molar ratio of zinc nitrate hexahydrate to HMTA, X-ray diffraction (XRD), scanning electron microscopy (SEM) images, Raman scattering, and photoluminescence (PL) spectroscopy were measured. XRD and SEM images are utilized to examine the crystalline quality as well as the morphological properties of the ZnO nanorods. It is found that morphology control can be achieved by simply adjusting the reactant concentrations and the molar ratio of zinc nitrate hexahydrate to HMTA. Raman scattering and PL spectroscopy measurements were demonstrated to study the size- and shape-dependent optical response of the ZnO nanorods. The Raman scattering result shows that the intensity of LO mode at around 576 cm{sup -1} decreases with the increase in the molar ratio of zinc nitrate hexahydrate to HMTA, indicating the reduction of defect concentrations in the synthesized ZnO nanorods. Room temperature PL spectrum of the synthesized ZnO nanorods reveals an ultraviolet (UV) emission peak and a broad visible emission. An enhancement of UV emission appears in the PL spectra as the molar ratio of zinc nitrate hexahydrate to HMTA increases, indicating that the defect concentration of the synthesized ZnO nanorods can be reduced by increasing the molar ratio. - Highlights: > Morphology of ZnO nanorods can be controlled via microwave-heating synthesis. > Molar ratio of Zn(NO{sub 3}){sub 2}.6H{sub 2}O to C{sub 6}H{sub 12}N{sub 4} affects the aspect ratio of ZnO nanorod. > ZnO nanorod showing higher aspect ratio can exhibit better optical properties.

  3. Photo-Detectors Integrated with Resonant Tunneling Diodes

    Directory of Open Access Journals (Sweden)

    José M. L. Figueiredo

    2013-07-01

    Full Text Available We report on photo-detectors consisting of an optical waveguide that incorporates a resonant tunneling diode (RTD. Operating at wavelengths around 1.55 μm in the optical communications C band we achieve maximum sensitivities of around 0.29 A/W which is dependent on the bias voltage. This is due to the nature of RTD nonlinear current-voltage characteristic that has a negative differential resistance (NDR region. The resonant tunneling diode photo-detector (RTD-PD can be operated in either non-oscillating or oscillating regimes depending on the bias voltage quiescent point. The oscillating regime is apparent when the RTD-PD is biased in the NDR region giving rise to electrical gain and microwave self-sustained oscillations Taking advantage of the RTD’s NDR distinctive characteristics, we demonstrate efficient detection of gigahertz (GHz modulated optical carriers and optical control of a RTD GHz oscillator. RTD-PD based devices can have applications in generation and optical control of GHz low-phase noise oscillators, clock recovery systems, and fiber optic enabled radio frequency communication systems.

  4. Temperature non-destructive testing by microwave radiometry: reduction of the frequency bandwidth; Controle non destructif de temperature par radiometrie micro-onde a bande etroite

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, L.; Vanoverschelde, C.; Sozanski, J.P.; Chive, M. [IEMN-UMR CNRS 9929, Dept. Hyperfrequences et Semi-Conducteurs, 59 - Villeneuve d' Ascq (France)

    1999-07-01

    Temperature is an important parameter for industrial process control. With the usual methods we obtain only an invasive or superficial information about temperature. Microwave radiometry is a non-invasive way to know the temperature within dissipative body. This paper presents the design of a new radiometer. With this system, the radiometric temperature is independent of the reflection coefficient of the captor. A simplified calibration takes into account insertion losses of the microwave elements. Radiometer frequency bandwidth has been greatly reduced and we present the first results. (authors)

  5. Broadband photonic microwave phase shifter based on controlling two RF modulation sidebands via a Fourier-domain optical processor.

    Science.gov (United States)

    Yang, J; Chan, E H W; Wang, X; Feng, X; Guan, B

    2015-05-04

    An all-optical photonic microwave phase shifter that can realize a continuous 360° phase shift over a wide frequency range is presented. It is based on the new concept of controlling the amplitude and phase of the two RF modulation sidebands via a Fourier-domain optical processor. The operating frequency range of the phase shifter is largely increased compared to the previously reported Fourier-domain optical processor based phase shifter that uses only one RF modulation sideband. This is due to the extension of the lower RF operating frequency by designing the amplitude and phase of one of the RF modulation sidebands while the other sideband is designed to realize the required RF signal phase shift. The two-sideband amplitude-and-phase-control based photonic microwave phase shifter has a simple structure as it only requires a single laser source, a phase modulator, a Fourier-domain optical processor and a single photodetector. Investigation on the bandwidth limitation problem in the conventional Fourier-domain optical processor based phase shifter is presented. Comparisons between the measured phase shifter output RF amplitude and phase responses with theory, which show excellent agreement, are also presented for the first time. Experimental results demonstrate the full -180° to + 180° phase shift with little RF signal amplitude variation of less than 3 dB and with a phase deviation of less than 4° over a 7.5 GHz to 26.5 GHz frequency range, and the phase shifter exhibits a long term stable performance.

  6. Shape-control by microwave-assisted hydrothermal method for the synthesis of magnetite nanoparticles using organic additives

    Energy Technology Data Exchange (ETDEWEB)

    Rizzuti, Antonino [Politecnico di Bari, Dipartimento di Ingegneria Civile, Ambientale, del Territorio, Edile e di Chimica (Italy); Dassisti, Michele [Politecnico di Bari, Dipartimento di Meccanica, Management e Matematica (Italy); Mastrorilli, Piero, E-mail: p.mastrorilli@poliba.it [Politecnico di Bari, Dipartimento di Ingegneria Civile, Ambientale, del Territorio, Edile e di Chimica (Italy); Sportelli, Maria C.; Cioffi, Nicola; Picca, Rosaria A. [Università di Bari, Dipartimento di Chimica (Italy); Agostinelli, Elisabetta; Varvaro, Gaspare [Consiglio Nazionale delle Ricerche, Istituto di Struttura della Materia (Italy); Caliandro, Rocco [Consiglio Nazionale delle Ricerche, Istituto di Cristallografia (Italy)

    2015-10-15

    A simple and fast microwave-assisted hydrothermal method is proposed for the synthesis of magnetite nanoparticles. The addition of different surfactants (polyvinylpyrrolidone, oleic acid, or trisodium citrate) was studied to investigate the effect on size distribution, morphology, and functionalization of the magnetite nanoparticles. Microwave irradiation at 150 °C for 2 h of aqueous ferrous chloride and hydrazine without additives resulted in hexagonal magnetite nanoplatelets with a facet-to-facet distance of 116 nm and a thickness of 40 nm having a saturation magnetization of ∼65 Am{sup 2} kg{sup −1}. The use of polyvinylpyrrolidone led to hexagonal nanoparticles with a facet-to-facet distance of 120 nm and a thickness of 53 nm with a saturation magnetization of ∼54 Am{sup 2} kg{sup −1}. Additives such as oleic acid and trisodium citrate yielded quasi-spherical nanoparticles of 25 nm in size with a saturation magnetization of ∼70 Am{sup 2} kg{sup −1} and spheroidal nanoparticles of 60 nm in size with a saturation magnetization up to ∼82 Am{sup 2} kg{sup −1}, respectively. A kinetic control of the crystal growth is believed to be responsible for the hexagonal habit of the nanoparticles obtained without additive. Conversely, a thermodynamic control of the crystal growth, leading to spheroidal nanoparticles, seems to occur when additives which strongly interact with the nanoparticle surface are used. A thorough characterization of the materials was performed. Magnetic properties were investigated by Superconducting Quantum Interference Device and Vibrating Sample magnetometers. Based on the observed magnetic properties, the magnetite obtained using citrate appears to be a promising support for magnetically transportable catalysts.

  7. Linear variable voltage diode capacitor and adaptive matching networks

    NARCIS (Netherlands)

    Larson, L.E.; De Vreede, L.C.N.

    2006-01-01

    An integrated variable voltage diode capacitor topology applied to a circuit providing a variable voltage load for controlling variable capacitance. The topology includes a first pair of anti-series varactor diodes, wherein the diode power-law exponent n for the first pair of anti-series varactor di

  8. Linear variable voltage diode capacitor and adaptive matching networks

    NARCIS (Netherlands)

    Larson, L.E.; De Vreede, L.C.N.

    2006-01-01

    An integrated variable voltage diode capacitor topology applied to a circuit providing a variable voltage load for controlling variable capacitance. The topology includes a first pair of anti-series varactor diodes, wherein the diode power-law exponent n for the first pair of anti-series varactor

  9. Semiconductor diode characterization for total skin electron irradiation.

    Science.gov (United States)

    Madrid González, O A; Rivera Montalvo, T

    2014-01-01

    In this paper, a semiconductor diode characterization was performed. The diode characterization was completed using an electron beam with 4 MeV of energy. The semiconductor diode calibration used irradiation with an electron beam in an ion chamber. "In vivo" dosimetry was also conducted. The dosimetry results revealed that the semiconductor diode was a good candidate for use in the total skin electron therapy (TSET) treatment control.

  10. Microwave Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Makes ultra-high-resolution field measurements. The Microwave Microscope (MWM) has been used in support of several NRL experimental programs involving sea...

  11. On Interactions of Microwave with Lightwave

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper addresses interactions of lightwave with microwave, and is divided into two parts. In part one, the background and the main topics of the research filed are introduced. In part two, some research activities at Shanghai University are reviewed.These include optical control of microwave devices, photoinduced electromagnetic radiation, lightwave interaction with superconductors, microwave control of lightwave, and the microwave approach to highly irregular fiber optics.

  12. Demonstration of frequency control and CW diode laser injection control of a titanium-doped sapphire ring laser with no internal optical elements

    Science.gov (United States)

    Bair, Clayton H.; Brockman, Philip; Hess, Robert V.; Modlin, Edward A.

    1988-01-01

    Theoretical and experimental frequency narrowing studies of a Ti:sapphire ring laser with no intracavity optical elements are reported. Frequency narrowing has been achieved using a birefringent filter between a partially reflecting reverse wave suppressor mirror and the ring cavity output mirror. Results of CW diode laser injection seeding are reported.

  13. Microwave-Assisted Hydrothermal Rapid Synthesis of Calcium Phosphates: Structural Control and Application in Protein Adsorption

    Directory of Open Access Journals (Sweden)

    Zhu-Yun Cai

    2015-07-01

    Full Text Available Synthetic calcium phosphate (CaP-based materials have attracted much attention in the biomedical field. In this study, we have investigated the effect of pH values on CaP nanostructures prepared using a microwave-assisted hydrothermal method. The hierarchical nanosheet-assembled hydroxyapatite (HAP nanostructure was prepared under weak acidic conditions (pH 5, while the HAP nanorod was prepared under neutral (pH 7 and weak alkali (pH 9 condition. However, when the pH value increases to 11, a mixed product of HAP nanorod and tri-calcium phosphate nanoparticle was obtained. The results indicated that the pH value of the initial reaction solution played an important role in the phase and structure of the CaP. Furthermore, the protein adsorption and release performance of the as-prepared CaP nanostructures were investigated by using hemoglobin (Hb as a model protein. The sample that was prepared at pH = 11 and consisted of mixed morphologies of nanorods and nanoprisms showed a higher Hb protein adsorption capacity than the sample prepared at pH 5, which could be explained by its smaller size and dispersed structure. The results revealed the relatively high protein adsorption capacity of the as-prepared CaP nanostructures, which show promise for applications in various biomedical fields such as drug delivery and protein adsorption.

  14. Controlled growth of Cu-Ni nanowires and nanospheres for enhanced microwave absorption properties

    Science.gov (United States)

    Wang, Xiaoxia; Dong, Lifeng; Zhang, Baoqin; Yu, Mingxun; Liu, Jingquan

    2016-03-01

    Copper is a good dielectric loss material but has low stability, whereas nickel is a good magnetic loss material and is corrosion resistant but with low conductivity, therefore Cu-Ni hybrid nanostructures have synergistic advantages as microwave absorption (MA) materials. Different Cu/Ni molar ratios of bimetallic nanowires (Cu13@Ni7, Cu5@Ni5 and Cu7@Ni13) and nanospheres (Cu13@Ni7, Cu5@Ni5 and Cu1@Ni3) have been successfully synthesized via facile reduction of hydrazine under similar reaction conditions, and the morphology can be easily tuned by varying the feed ratio or the complexing agent. Apart from the concentrations of Cu2+ and Ni2+, the reduction parameters are similar for all samples to confirm the effects of the Cu/Ni molar ratio and morphology on MA properties. Ni is incorporated into the Cu-Ni nanomaterials as a shell over the Cu core at low temperature, as proved by XRD, SEM, TEM and XPS. Through the complex relative permittivity and permeability, reflection loss was evaluated, which revealed that the MA capacity greatly depended on the Cu/Ni molar ratio and morphology. For Cu@Ni nanowires, as the molar ratio of Ni shell increased the MA properties decreased accordingly. However, for Cu@Ni nanospheres, the opposite trend was found, that is, as the molar ratio of the Ni shell increased the MA properties increased.

  15. Microwave radiation effects on the different stages of Sitophilus oryzae (Linne, 1763) (Coleoptera, Curculionidae) evolutive cycle in rice, focusing its control

    Energy Technology Data Exchange (ETDEWEB)

    Franco, Jose G.; Franco, Suely S.H., E-mail: gilmita@uol.com.br, E-mail: zegilmar60@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Franco, Caio H.; Arthur, Paula B.; Arthur, Valter, E-mail: caiohaddadfranco@lnbio.cnpem.com.br, E-mail: arthur@cena.usp.br [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil). Lab. de Radiobiologia e Ambiente

    2013-07-01

    As insects increase in radio tolerance as they develop and usually several developmental stages of pest may present in grain shipped commodity, it is important to know the microwave radiation susceptibility of stages of the target insect before the establishment of microwave radiation quarantine treatments. The current research had the aim to evaluate the microwave radiation effects on several phases of the rice weevil evolution cycle (S.oryzae), focusing its control. This specie is considered as on of the most serious worldwide pests for stored grains. The tests have been done in glass vials with 250 grams of whole grain (brown) rice and the irradiation was done in a 2,450 MHz commercial microwave oven, model Carousel II (potency of 800W). It was determined the exposure time needed to each phase control for the insect evolutive cycle, concluding that the immature phases (larvae and pupae), contained inside the rice, are more sensitive, requiring only 100 seconds to obtain 100% control while the egg phase requires a longer exposure (130 seconds). Referring to the grown phase, the time required to attain the lethal dose was 160 seconds. All the exposure time have been irradiated with a low potency (240 W). It also displayed that to greater quantities of rice (1.0 kg), with egg presence and forming a 2.0-centimeter layer on the microwave plate surface, it required an exposure time of 180 seconds. Therefore, in a more effective way, we can recommend these 180 seconds exposure time to the control of all phases concerning the insect evolutive cycle. (author)

  16. The Annular Microwave Dryer Design and Study on Honeysuckle

    Directory of Open Access Journals (Sweden)

    Geng Yuefeng

    2014-03-01

    Full Text Available In order to dry fresh honeysuckle, microwave drying process were studied on fresh honeysuckle; and microwave drying apparatus on fresh honeysuckle is designed according to the drying process. The designed microwave dryer contains microwave generator, microwave dryer, dehumidifying systems, control system, transmission systems, microwave leakage inhibited mechanism and other components. The drying experiment is carried by the designed dryer, from the setting-to-work test, the design was success.

  17. Coaxial foilless diode

    OpenAIRE

    Long Kong; QingXiang Liu; XiangQiang Li; ShaoMeng Wang

    2014-01-01

    A kind of coaxial foilless diode is proposed in this paper, with the structure model and operating principle of the diode are given. The current-voltage relation of the coaxial foilless diode and the effects of structure parameters on the relation are studied by simulation. By solving the electron motion equation, the beam deviation characteristic in the presence of external magnetic field in transmission process is analyzed, and the relationship between transverse misalignment with diode par...

  18. Coaxial foilless diode

    OpenAIRE

    Long Kong; QingXiang Liu; XiangQiang Li; ShaoMeng Wang

    2014-01-01

    A kind of coaxial foilless diode is proposed in this paper, with the structure model and operating principle of the diode are given. The current-voltage relation of the coaxial foilless diode and the effects of structure parameters on the relation are studied by simulation. By solving the electron motion equation, the beam deviation characteristic in the presence of external magnetic field in transmission process is analyzed, and the relationship between transverse misalignment with diode par...

  19. Header For Laser Diode

    Science.gov (United States)

    Rall, Jonathan A. R.; Spadin, Paul L.

    1990-01-01

    Header designed to contain laser diode. Output combined incoherently with outputs of other laser diodes in grating laser-beam combiner in optical communication system. Provides electrical connections to laser diode, cooling to thermally stabilize laser operation, and optomechanical adjustments that steer and focus laser beam. Range of adjustments provides for correction of worst-case decentering and defocusing of laser beam encountered with laser diodes. Mechanical configuration made simple to promote stability and keep cost low.

  20. Thermal-Diode Sandwich Panel

    Science.gov (United States)

    Basiulis, A.

    1986-01-01

    Thermal diode sandwich panel transfers heat in one direction, but when heat load reversed, switches off and acts as thermal insulator. Proposed to control temperature in spacecraft and in supersonic missiles to protect internal electronics. In combination with conventional heat pipes, used in solar panels and other heat-sensitive systems.

  1. Spin-photon entangling diode

    DEFF Research Database (Denmark)

    Flindt, Christian; Sørensen, A. S.; Lukin, M. D.;

    2007-01-01

    We propose a semiconductor device that can electrically generate entangled electron spin-photon states, providing a building block for entanglement of distant spins. The device consists of a p-i-n diode structure that incorporates a coupled double quantum dot. We show that electronic control of t...

  2. Bilayer avalanche spin-diode logic

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, Joseph S., E-mail: joseph.friedman@u-psud.fr; Querlioz, Damien [Institut d’Electronique Fondamentale, Univ. Paris-Sud, CNRS, 91405 Orsay (France); Fadel, Eric R. [Department of Materials Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Wessels, Bruce W. [Department of Electrical Engineering & Computer Science, Northwestern University, Evanston, IL 60208 (United States); Department of Materials Science & Engineering, Northwestern University, Evanston, IL 60208 (United States); Sahakian, Alan V. [Department of Electrical Engineering & Computer Science, Northwestern University, Evanston, IL 60208 (United States); Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208 (United States)

    2015-11-15

    A novel spintronic computing paradigm is proposed and analyzed in which InSb p-n bilayer avalanche spin-diodes are cascaded to efficiently perform complex logic operations. This spin-diode logic family uses control wires to generate magnetic fields that modulate the resistance of the spin-diodes, and currents through these devices control the resistance of cascaded devices. Electromagnetic simulations are performed to demonstrate the cascading mechanism, and guidelines are provided for the development of this innovative computing technology. This cascading scheme permits compact logic circuits with switching speeds determined by electromagnetic wave propagation rather than electron motion, enabling high-performance spintronic computing.

  3. PROGRAMMING THE MICROWAVE-OVEN

    NARCIS (Netherlands)

    KOK, LP; VISSER, PE; BOON, ME

    1994-01-01

    Microwaves can be used to stimulate chemical bonding, diffusion of reagents into and out of the specimen, and coagulation processes in preparatory techniques. Temperature plays an important role in these processes. There are several ways of controlling the temperature of microwave-exposed tissue, fl

  4. PROGRAMMING THE MICROWAVE-OVEN

    NARCIS (Netherlands)

    KOK, LP; VISSER, PE; BOON, ME

    1994-01-01

    Microwaves can be used to stimulate chemical bonding, diffusion of reagents into and out of the specimen, and coagulation processes in preparatory techniques. Temperature plays an important role in these processes. There are several ways of controlling the temperature of microwave-exposed tissue,

  5. Control of pn-junction turn-on voltage in 4H-SiC merged PiN Schottky diode

    Science.gov (United States)

    Park, Junbo; Park, Kun-Sik; Won, Jong-il; Kim, Ki-hwan; Koo, Sangmo; Kim, Sang-gi; Mun, Jae-Kyoung

    2017-04-01

    We present numerical simulation results and experimental measurements that explain the physical mechanism behind the high critical voltage, Vcrit, required to turn on a pn junction in a merged PiN Schottky (MPS) diode. The 2D simulation of potential distribution within a unit MPS cell demonstrated that the potential gradient set by the Schottky junction raises the potential barrier formed at the pn junction, thereby increasing Vcrit. Based on this knowledge, we propose that changing the ratio of the Schottky contact and the p+ region area, as well as shallow p-doping of the Schottky interface, can be used to control the magnitude of Vcrit. We present simulation and measurement results that demonstrate the feasibility of our approach.

  6. Lighting with laser diodes

    Science.gov (United States)

    Basu, Chandrajit; Meinhardt-Wollweber, Merve; Roth, Bernhard

    2013-08-01

    Contemporary white light-emitting diodes (LEDs) are much more efficient than compact fluorescent lamps and hence are rapidly capturing the market for general illumination. LEDs are also replacing halogen lamps or even newer xenon based lamps in automotive headlamps. Because laser diodes are inherently much brighter and often more efficient than corresponding LEDs, there is great research interest in developing laser diode based illumination systems. Operating at higher current densities and with smaller form factors, laser diodes may outperform LEDs in the future. This article reviews the possibilities and challenges in the integration of visible laser diodes in future illumination systems.

  7. Laser Diode Ignition (LDI)

    Science.gov (United States)

    Kass, William J.; Andrews, Larry A.; Boney, Craig M.; Chow, Weng W.; Clements, James W.; Merson, John A.; Salas, F. Jim; Williams, Randy J.; Hinkle, Lane R.

    1994-01-01

    This paper reviews the status of the Laser Diode Ignition (LDI) program at Sandia National Labs. One watt laser diodes have been characterized for use with a single explosive actuator. Extensive measurements of the effect of electrostatic discharge (ESD) pulses on the laser diode optical output have been made. Characterization of optical fiber and connectors over temperature has been done. Multiple laser diodes have been packaged to ignite multiple explosive devices and an eight element laser diode array has been recently tested by igniting eight explosive devices at predetermined 100 ms intervals.

  8. Influence of Temperature on the Performance of a Spin-Torque Microwave Detector

    Science.gov (United States)

    2012-11-01

    temperatures. Index Terms—Microwave detector, noise properties, spin-transfer torque, temperature. I. INTRODUCTION T HE spin-transfer-torque ( STT ...oscillations under the action of a DC electric current [5]–[10], [14]. Another manifestation of STT , so-called spin torque diode effect [11]–[13], can...determination of the STT parameters [15], [16]. The spin torque diode effect is a quadratic rectification ef- fect of the input microwave current in a

  9. Optimization of the accelerated curing process of concrete using a fibre Bragg grating-based control system and microwave technology

    Science.gov (United States)

    Fabian, Matthias; Jia, Yaodong; Shi, Shi; McCague, Colum; Bai, Yun; Sun, Tong; Grattan, Kenneth T. V.

    2016-05-01

    In this paper, an investigation into the suitability of using fibre Bragg gratings (FBGs) for monitoring the accelerated curing process of concrete in a microwave heating environment is presented. In this approach, the temperature data provided by the FBGs are used to regulate automatically the microwave power so that a pre-defined temperature profile is maintained to optimize the curing process, achieving early strength values comparable to those of conventional heat-curing techniques but with significantly reduced energy consumption. The immunity of the FBGs to interference from the microwave radiation used ensures stable readings in the targeted environment, unlike conventional electronic sensor probes.

  10. Microwave Measurements

    CERN Document Server

    Skinner, A D

    2007-01-01

    The IET has organised training courses on microwave measurements since 1983, at which experts have lectured on modern developments. Their lecture notes were first published in book form in 1985 and then again in 1989, and they have proved popular for many years with a readership beyond those who attended the courses. The purpose of this third edition of the lecture notes is to bring the latest techniques in microwave measurements to this wider audience. The book begins with a survey of the theory of current microwave circuits and continues with a description of the techniques for the measureme

  11. Microwave photonics

    CERN Document Server

    Lee, Chi H

    2006-01-01

    Wireless, optical, and electronic networks continue to converge, prompting heavy research into the interface between microwave electronics, ultrafast optics, and photonic technologies. New developments arrive nearly as fast as the photons under investigation, and their commercial impact depends on the ability to stay abreast of new findings, techniques, and technologies. Presenting a broad yet in-depth survey, Microwave Photonics examines the major advances that are affecting new applications in this rapidly expanding field.This book reviews important achievements made in microwave photonics o

  12. Microwave generator

    Science.gov (United States)

    Kwan, T.J.T.; Snell, C.M.

    1987-03-31

    A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit there through effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators. 6 figs.

  13. Microwave photonics

    CERN Document Server

    Lee, Chi H

    2013-01-01

    Microwave photonics continues to see rapid growth. The integration of optical fiber and wireless networks has become a commercial reality and is becoming increasingly pervasive. Such hybrid technology will lead to many innovative applications, including backhaul solutions for mobile networks and ultrabroadband wireless networks that can provide users with very high bandwidth services. Microwave Photonics, Second Edition systematically introduces important technologies and applications in this emerging field. It also reviews recent advances in micro- and millimeter-wavelength and terahertz-freq

  14. Control of a White Organic Light Emitting Diode emission parameters using a single doped RGB active layer

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, D. [Departamento de Ciência dos Materiais e i3N – Instituto de Nanoestruturas, Nanomodelação e Nanofabricação, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica (Portugal); Pinto, A.; Califórnia, A.; Gomes, J. [CeNTI – Centro de Nanotecnologia, Materiais Técnicos, Funcionais e Inteligentes, Rua Fernando Mesquita 2785, 4760-034 Vila Nova de Famalicão (Portugal); Pereira, L., E-mail: luiz@ua.pt [Departmento de Física e i3N – Instituto de Nanoestruturas, Nanomodelação e Nanofabricação, Universidade de Aveiro, 3810-193 Aveiro (Portugal)

    2016-09-15

    Highlights: • A simple WOLED for Solid State Lighting is proposed with high color stability. • Energy transfer and electroluminescence dynamics of a single RGB layer for WOLEDs. • White shade modulation and stability over large emitting areas and applied voltages. - Abstract: Solid State Lighting technologies based on Organic Light Emitting Diodes, became an interesting focus due to their unique properties. The use of a unique RGB active layer for white emission, although simple in theory, shows difficulty to stabilize both CIE coordinates and color modulation. In this work, a WOLED using a simple RGB layer, was developed achieving a high color stability and shade modulation. The RGB matrix comprises a blue host material NPB, doped with two guests, a green (Coumarin 153) and a red (DCM1) in low concentrations. The RGB layer carrier dynamics allows for the white emission in low device complexity and high stability. This was also shown independent of the white shade, obtained through small changes in the red dopant resulting in devices ranging from warm to cool white i.e. an easy color tuning. A detailed analysis of the opto-electrical behavior is made.

  15. Adjunctive use of combination of super-pulsed laser and light-emitting diodes phototherapy on nonspecific knee pain: double-blinded randomized placebo-controlled trial.

    Science.gov (United States)

    Leal-Junior, Ernesto Cesar Pinto; Johnson, Douglas Scott; Saltmarche, Anita; Demchak, Timothy

    2014-11-01

    Phototherapy with low-level laser therapy (LLLT) and light-emitting diode therapy (LEDT) has arisen as an interesting alternative to drugs in treatments of musculoskeletal disorders. However, there is a lack of studies investigating the effects of combined use of different wavelengths from different light sources like lasers and light-emitting diodes (LEDs) in skeletal muscle disorders. With this perspective in mind, this study aimed to investigate the effects of phototherapy with combination of different light sources on nonspecific knee pain. It was performed a randomized, placebo-controlled, double-blinded clinical trial. Eighty-six patients rated 30 or greater on the pain visual analogue scale (VAS) were recruited and included in study. Patients of LLLT group received 12 treatments with active phototherapy (with 905 nm super-pulsed laser and 875 and 640 nm LEDs, Manufactured by Multi Radiance Medical, Solon, OH, USA) and conventional treatment (physical therapy or chiropractic care), and patients of placebo group were treated at same way but with placebo phototherapy device. Pain assessments (VAS) were performed at baseline, 4th, 7th, and 10th treatments, after the completion of treatments and at 1-month follow-up visit. Quality of life assessments (SF-36®) were performed at baseline, after the completion of treatments and at 1-month follow-up visit. Our results demonstrate that phototherapy significantly decreased pain (p physical component summary at posttreatments and follow-up assessments compared to placebo. We conclude that combination of super-pulsed laser, red and infrared LEDs is effective to decrease pain and improve quality of life in patients with knee pain.

  16. Estimation of Most Favorable Optical Window Position Subject to Achieve Finest Optical Control of Lateral DDR IMPATT Diode Designed to Operate at W-Band

    Directory of Open Access Journals (Sweden)

    A. Acharyya

    2014-06-01

    Full Text Available The optimum position of the optical window (OW of illuminated lateral double-drift region (DDR impact avalanche transit time (IMPATT device has been determined subject to achieve the finest optical control of both DC and RF properties of the device. The OW is a tiny hole that has to be created on the oxide layer through which the light energy of appropriate wavelength can be coupled to the space charge region of the device. A non-sinusoidal voltage is assumed to be applied across the diode and the corresponding terminal current response is obtained from a two-dimensional (2-D large-signal (L-S simulation technique developed by the authors for illuminated lateral DDR IMPATT diode. Both the DC and L-S properties of the illuminated device based on Si, designed to operate at W-band frequencies (75 – 110 GHz are obtained from the said L-S simulation. Simulation is carried out for different incident optical power levels of different wavelengths (600 – 1000 nm by varying the position of the fixed sized OW on the oxide layer along the direction of electrical conduction of the device. Results show that, the most favorable optical tuning can be achieved when the OW is entirely created over the p-type depletion layer, i.e. when the photocurrent is purely electron dominated. Also the 700 nm wavelength is found to be most suitable wavelength for obtaining the maximum optical modulation of both DC and RF properties of the device.

  17. Stabilizing Microwave Frequency of a Photonic Oscillator

    Science.gov (United States)

    Maleki, Lute; Yu, Nan; Tu, Meirong

    2006-01-01

    having a very high value of the resonance quality factor (Q). The optical frequency of MLL is then stabilized by locking it to an atomic transition as described below. The COEO contains a tunable 1-nm band-pass optical filter and a piezoelectric-transducer (PZT) drum over which a stretch of fiber is wound. The 1-nm-wide pass band of the filter provides coarse tuning to overlap the frequency comb with the atomic transition frequency. Controlled stretching of the fiber by means of the PZT drum can be used in conjunction with temperature control for locking the laser frequency. To reference to an atomic resonance at 780 nm in this demonstration setup, the optical output of the COEO at 1,560 nm is fed through an erbium-doped-fiber amplifier (EDFA) to a frequency doubler in the form of a periodically poled lithium niobate (PPLN) crystal. The frequency-doubled output is combined with the output of a separate frequency-stabilized diode laser at a photodetector. As described thus far, the two 780-nm laser subsystems are nominally independent of each other and can, therefore, operate at different frequencies. Hence, at the photodetector, the two laser beams interfere, so that the output of the photodetector includes a beat note (a component at the difference between the two laser frequencies).

  18. Improved Thermoelectrically Cooled Laser-Diode Assemblies

    Science.gov (United States)

    Glesne, Thomas R.; Schwemmer, Geary K.; Famiglietti, Joe

    1994-01-01

    Cooling decreases wavelength and increases efficiency and lifetime. Two improved thermoelectrically cooled laser-diode assemblies incorporate commercial laser diodes providing combination of both high wavelength stability and broad wavelength tuning which are broadly tunable, highly stable devices for injection seeding of pulsed, high-power tunable alexandrite lasers used in lidar remote sensing of water vapor at wavelengths in vicinity of 727 nanometers. Provide temperature control needed to take advantage of tunability of commercial AlGaAs laser diodes in present injection-seeding application.

  19. Controlled Microwave-Assisted Growth of Monodisperse of Silica Nanoparticles under Acid Catalysis (Postprint)

    Science.gov (United States)

    2012-11-26

    over conventional heating techniques because they deliver large amounts of controlled power quickly to small volumes of absorbing media, promoting...transition states, such as pentacoordinate and hexacoordinate silanes .25,38,39 Recently, a DFT study has postulated that the formation of stable silica

  20. Perpetual factors involved in performance of air traffic controllers using a microwave landing system

    Science.gov (United States)

    Gershzohn, G.

    1978-01-01

    The task involved the control of two simulated aircraft targets per trial, in a 37.0 -km radius terminal area, by means of conventional radar vectoring and/or speed control. The goal was to insure that the two targets crossed the Missed Approach Point (MAP) at the runway threshold exactly 60 sec apart. The effects on controller performance of the MLS configuration under wind and no-wind conditions were examined. The data for mean separation time between targets at the MAP and the range about that mean were analyzed by appropriate analyses of variance. Significant effects were found for mean separation times as a result of the configuration of the MLS and for interaction between the configuration and wind conditions. The analysis of variance for range indicated significantly poorer performance under the wind condition. These findings are believed to be a result of certain perceptual factors involved in radar air traffic control (ATC) using the MLS with separation of targets in time.

  1. Microwave Assisted Drug Delivery

    DEFF Research Database (Denmark)

    Jónasson, Sævar Þór; Zhurbenko, Vitaliy; Johansen, Tom Keinicke

    2014-01-01

    In this work, the microwave radiation is adopted for remote activation of pharmaceutical drug capsules inside the human body in order to release drugs at a pre-determined time and location. An array of controllable transmitting sources is used to produce a constructive interference at a certain...... focus point inside the body, where the drugs are then released from the specially designed capsules. An experimental setup for microwave activation has been developed and tested on a body phantom that emulates the human torso. A design of sensitive receiving structures for integration with a drug...

  2. Microwave Assisted Drug Delivery

    DEFF Research Database (Denmark)

    Jónasson, Sævar Þór; Zhurbenko, Vitaliy; Johansen, Tom Keinicke

    2014-01-01

    In this work, the microwave radiation is adopted for remote activation of pharmaceutical drug capsules inside the human body in order to release drugs at a pre-determined time and location. An array of controllable transmitting sources is used to produce a constructive interference at a certain...... focus point inside the body, where the drugs are then released from the specially designed capsules. An experimental setup for microwave activation has been developed and tested on a body phantom that emulates the human torso. A design of sensitive receiving structures for integration with a drug...

  3. Terahertz Diode Development

    Science.gov (United States)

    2009-03-23

    Gunn Diode , Negative Differential Resistance, Ballistic Transport, GaN, THz, Co-planar Resonator 16. SECURITY CLASSIFICATION OF: REPORT U b...Report DATES COVERED (From - Jo) 1 January 2004- 31 December 2008 4. TITLE AND SUBTITLE Terahertz Diode Development 5a. CONTRACT NUMBER N00014...current-voltage oscillations at the terminals of the diode at a frequency which is, to first order, determined by the average transit time of the EAL

  4. Synthesis of morphology-controlled ZnO microstructures via a microwave-assisted hydrothermal method and their gas-sensing property.

    Science.gov (United States)

    Liang, Sa; Zhu, Lianfeng; Gai, Guosheng; Yao, Youwei; Huang, Jue; Ji, Xuewen; Zhou, Xiaoming; Zhang, Dongyun; Zhang, Peixin

    2014-07-01

    Controllable ZnO architectures with flower-like and rod-like morphologies were synthesized via a microwave-assisted hydrothermal method. By adjusting the concentration of Zn(2+) in the aqueous precursors, different morphologies of ZnO microstructures were obtained. The size of ZnO was uniform after ultrasonic treatment. The growth process of ZnO in solution was studied by monitoring the intermediate products, which were extracted at different stages of the reactions: (i) precursor preparation, (ii) microwave irradiation heating, (iii) natural cooling. Studies of the SEM images and XRD data revealed that the formation of ZnO occurred via in situ assembly or dissolution-reprecipitation of zinc hydroxide complexes. The morphology-dependent ethanol sensing performance was observed; the seven-spine ZnO structures exhibit the highest activity.

  5. A Preliminary In Vitro Study on the Efficacy of High-Power Photodynamic Therapy (HLLT): Comparison between Pulsed Diode Lasers and Superpulsed Diode Lasers and Impact of Hydrogen Peroxide with Controlled Stabilization

    Science.gov (United States)

    Baldoni, Marco; Ghisalberti, Carlo Angelo; Paiusco, Alessio

    2016-01-01

    Aim. In periodontology lasers have been suggested for the photodynamic therapy (PDT): such therapy can be defined as the inactivation of cells, microorganisms, or molecules induced by light and not by heat. The aim of this study was to evaluate results of PDT using a 980 nm diode laser (Wiser Doctor Smile, Lambda SPA, Italy) combined with hydrogen peroxide, comparing a pulsed diode laser (LI) activity to a high-frequency superpulsed diode laser (LII). Materials and Methods. Primary fibroblasts and keratinocytes cell lines, isolated from human dermis, were irradiated every 48 h for 10 days using LI and LII combined with SiOxyL+™ Solution (hydrogen peroxide (HP) stabilized with a glycerol phosphate complex). Two days after the last irradiation, the treated cultures were analyzed by flow cytofluorometry (FACS) and western blotting to quantify keratin 5 and keratin 8 with monoclonal antibodies reactive to cytokeratin 5 and cytokeratin 8. Antimicrobial activity was also evaluated. Results. Both experimental models show the superiority of LII against LI. In parallel, stabilized HP provided better results in the regeneration test in respect to common HP, while the biocidal activity remains comparable. Conclusion. The use of high-frequency lasers combined with stabilized hydrogen peroxide can provide optimal results for a substantial decrease of bacterial count combined with a maximal biostimulation induction of soft tissues and osteogenesis. PMID:27631000

  6. A Preliminary In Vitro Study on the Efficacy of High-Power Photodynamic Therapy (HLLT): Comparison between Pulsed Diode Lasers and Superpulsed Diode Lasers and Impact of Hydrogen Peroxide with Controlled Stabilization.

    Science.gov (United States)

    Caccianiga, Gianluigi; Baldoni, Marco; Ghisalberti, Carlo Angelo; Paiusco, Alessio

    2016-01-01

    Aim. In periodontology lasers have been suggested for the photodynamic therapy (PDT): such therapy can be defined as the inactivation of cells, microorganisms, or molecules induced by light and not by heat. The aim of this study was to evaluate results of PDT using a 980 nm diode laser (Wiser Doctor Smile, Lambda SPA, Italy) combined with hydrogen peroxide, comparing a pulsed diode laser (LI) activity to a high-frequency superpulsed diode laser (LII). Materials and Methods. Primary fibroblasts and keratinocytes cell lines, isolated from human dermis, were irradiated every 48 h for 10 days using LI and LII combined with SiOxyL(+) ™ Solution (hydrogen peroxide (HP) stabilized with a glycerol phosphate complex). Two days after the last irradiation, the treated cultures were analyzed by flow cytofluorometry (FACS) and western blotting to quantify keratin 5 and keratin 8 with monoclonal antibodies reactive to cytokeratin 5 and cytokeratin 8. Antimicrobial activity was also evaluated. Results. Both experimental models show the superiority of LII against LI. In parallel, stabilized HP provided better results in the regeneration test in respect to common HP, while the biocidal activity remains comparable. Conclusion. The use of high-frequency lasers combined with stabilized hydrogen peroxide can provide optimal results for a substantial decrease of bacterial count combined with a maximal biostimulation induction of soft tissues and osteogenesis.

  7. SiC Schottky diode electrothermal macromodel

    OpenAIRE

    Masana Nadal, Francisco

    2010-01-01

    This paper presents a SiC Schottky diode model including static, dynamic and thermal features implemented as separate parameterized blocks constructed from SPICE Analog Behavioral Modeling (ABM) controlled sources. The parameters for each block are easy to extract, even from readily available diode data sheet information. The model complexity is low thus allowing reasonably long simulation times to cope with the rather slow self heating process and yet accurate enough for practical purposes.

  8. Compact tunable microwave filter using retroreflective acousto-optic filtering and delay controls.

    Science.gov (United States)

    Riza, Nabeel A; Ghauri, Farzan N

    2007-03-01

    Programmable broadband rf filters are demonstrated using a compact retroreflective optical design with an acousto-optic tunable filter and a chirped fiber Bragg grating. This design enables fast 34 micros domain analog-mode control of rf filter time delays and weights. Two proof-of-concept filters are demonstrated including a two-tap notch filter with >35 dB notch depth and a four-tap bandpass filter. Both filters have 2-8 GHz tunability and a 34 micros reset time.

  9. P-type nitrogen-doped ZnO nanostructures with controlled shape and doping level by facile microwave synthesis.

    Science.gov (United States)

    Herring, Natalie P; Panchakarla, Leela S; El-Shall, M Samy

    2014-03-04

    We report herein the development of a facile microwave irradiation (MWI) method for the synthesis of high-quality N-doped ZnO nanostructures with controlled morphology and doping level. We present two different approaches for the MWI-assisted synthesis of N-doped ZnO nanostructures. In the first approach, N-doping of Zn-poor ZnO prepared using zinc peroxide (ZnO2) as a precursor is carried out under MWI in the presence of urea as a nitrogen source and oleylamine (OAm) as a capping agent for the shape control of the resulting N-doped ZnO nanostructures. Our approach utilizes the MWI process for the decomposition of ZnO2, where the rapid transfer of energy directly to ZnO2 can cause an instantaneous internal temperature rise and, thus, the activation energy for the ZnO2 decomposition is essentially decreased as compared to the decomposition under conductive heating. In the second synthesis method, a one-step synthesis of N-doped ZnO nanostructures is achieved by the rapid decomposition of zinc acetate in a mixture of urea and OAm under MWI. We demonstrate, for the first time, that MWI decomposition of zinc acetate in a mixture of OAm and urea results in the formation of N-doped nanostructures with controlled shape and N-doping level. We report a direct correlation between the intensity of the Raman scattering bands in N-doped ZnO and the concentration of urea used in the synthesis. Electrochemical measurements demonstrate the successful synthesis of stable p-type N-doped ZnO nanostructures using the one-step MWI synthesis and, therefore, allow us to investigate, for the first time, the relationship between the doping level and morphology of the ZnO nanostructures. The results provide strong evidence for the control of the electrical behavior and the nanostructured shapes of ZnO nanoparticles using the facile MWI synthesis method developed in this work.

  10. Emission Spectral Control of a Silicon Light Emitting Diode Fabricated by Dressed-Photon-Phonon Assisted Annealing Using a Short Pulse Pair

    Directory of Open Access Journals (Sweden)

    Tadashi Kawazoe

    2014-01-01

    Full Text Available We fabricated a high-efficiency infrared light emitting diode (LED via dressed-photon-phonon (DPP assisted annealing of a p-n homojunctioned bulk Si crystal. The center wavelength in the electroluminescence (EL spectrum of this LED was determined by the wavelength of a CW laser used in the DPP-assisted annealing. We have proposed a novel method of controlling the EL spectral shape by additionally using a pulsed light source in order to control the number of phonons for the DPP-assisted annealing. In this method, the Si crystal is irradiated with a pair of pulses having an arrival time difference between them. The number of coherent phonons created is increased (reduced by tuning (detuning this time difference. A Si-LED was subjected to DPP-assisted annealing using a 1.3 μm (hν=0.94 eV CW laser and a mode-locked pulsed laser with a pulse width of 17 fs. When the number of phonons was increased, the EL emission spectrum broadened toward the high-energy side by 200 meV or more. The broadening towards the low-energy side was reduced to 120 meV.

  11. High-power, computer-controlled, light-emitting diode-based light sources for fluorescence imaging and image-guided surgery.

    Science.gov (United States)

    Gioux, Sylvain; Kianzad, Vida; Ciocan, Razvan; Gupta, Sunil; Oketokoun, Rafiou; Frangioni, John V

    2009-01-01

    Optical imaging requires appropriate light sources. For image-guided surgery, in particular fluorescence-guided surgery, a high fluence rate, a long working distance, computer control, and precise control of wavelength are required. In this article, we describe the development of light-emitting diode (LED)-based light sources that meet these criteria. These light sources are enabled by a compact LED module that includes an integrated linear driver, heat dissipation technology, and real-time temperature monitoring. Measuring only 27 mm wide by 29 mm high and weighing only 14.7 g, each module provides up to 6,500 lx of white (400-650 nm) light and up to 157 mW of filtered fluorescence excitation light while maintaining an operating temperature mW/cm2 of 670 nm near-infrared (NIR) fluorescence excitation light, and 14.0 mW/cm2 of 760 nm NIR fluorescence excitation light over a 15 cm diameter field of view. Using this light source, we demonstrated NIR fluorescence-guided surgery in a large-animal model.

  12. Simultaneous determination of five marker compounds in Xuanfu Daizhe Tang by high-performance liquid chromatography coupled with diode array detection for quality control

    Directory of Open Access Journals (Sweden)

    Kunming Qin

    2012-01-01

    Full Text Available Background: Xuanfu Daizhe Tang (XDT is a classical traditional Chinese medicinal prescription that has been widely used for treating digestive system illnesses for hundreds of years. Materials and Methods: In this study, a simple and sensitive high-performance liquid chromatography coupled with diode array detection (HPLC-DAD method was established for the simultaneous determination of five marker compounds in XDT including chlorogenic acid, glycyrrhizic acid, ginsenoside Rg1, ginsenoside Rb1 and ginsenoside Re, for quality control of this well-known traditional Chinese medicine (TCM. Results: These compounds were separated in less than 130 min using a YMC C18 column with a gradient elution system of acetonitrile and 0.1% phosphoric acid water solution at a flow rate of 1 ml/min. All calibration curves of standard components showed good linearity with R 2 >0.9991. Limit of detection and limit of quantification varied from 0.11 to 4.3 μg/ml and 0.20 to 11.6 μg/ml, respectively. The relative standard deviations (RSDs of the intra-day and inter-day experiments were less than 4.72 and 5.48%, respectively. The accuracy of recovery test ranged from 95.0 to 105.0% with RSD values 1.28- 4.32%. Conclusion: The validated method is simple, reliable, and successfully applied to determine the contents of the selected compounds in XDT for quality control.

  13. Qualification and Selection of Flight Diode Lasers for Space Applications

    Science.gov (United States)

    Liebe, Carl C.; Dillon, Robert P.; Gontijo, Ivair; Forouhar, Siamak; Shapiro, Andrew A.; Cooper, Mark S.; Meras, Patrick L.

    2010-01-01

    The reliability and lifetime of laser diodes is critical to space missions. The Nuclear Spectroscopic Telescope Array (NuSTAR) mission includes a metrology system that is based upon laser diodes. An operational test facility has been developed to qualify and select, by mission standards, laser diodes that will survive the intended space environment and mission lifetime. The facility is situated in an electrostatic discharge (ESD) certified clean-room and consist of an enclosed temperature-controlled stage that can accommodate up to 20 laser diodes. The facility is designed to characterize a single laser diode, in addition to conducting laser lifetime testing on up to 20 laser diodes simultaneously. A standard laser current driver is used to drive a single laser diode. Laser diode current, voltage, power, and wavelength are measured for each laser diode, and a method of selecting the most adequate laser diodes for space deployment is implemented. The method consists of creating histograms of laser threshold currents, powers at a designated current, and wavelengths at designated power. From these histograms, the laser diodes that illustrate a performance that is outside the normal are rejected and the remaining lasers are considered spaceborne candidates. To perform laser lifetime testing, the facility is equipped with 20 custom laser drivers that were designed and built by California Institute of Technology specifically to drive NuSTAR metrology lasers. The laser drivers can be operated in constant-current mode or alternating-current mode. Situated inside the enclosure, in front of the laser diodes, are 20 power-meter heads to record laser power throughout the duration of lifetime testing. Prior to connecting a laser diode to the current source for characterization and lifetime testing, a background program is initiated to collect current, voltage, and resistance. This backstage data collection enables the operational test facility to have full laser diode

  14. APPLICATION OF MICROWAVE TECHNOLOGY IN OIL POLLUTION CONTROL%微波技术在石油污染治理中的应用

    Institute of Scientific and Technical Information of China (English)

    黄维秋; 王丹莉; 李峰; 王卫卿

    2011-01-01

    石油污染会造成严重的环境污染,还会对人的身体健康造成严重的危害。就微波技术在含油废水的处理、石油污染土壤的修复、油气吸附剂的再生方面做了详细的阐述,指出了微波技术在石油污染治理领域应用的优缺点,重点提出了在油气吸附回收工艺中,应用微波/真空或微波/超声波集成再生技术的研究思路。%Oil pollution can lead to serious harmful effects on people and the environment.The applications of microwave technology to control the oil pollution,such as treatment of oily wastewater,remedy of soil contaminated with oil,regeneration of oil vapor adsorbents,were introduced and analyzed in detail.The advantages and disadvantages of the applications were also discussed and compared.Then,the key research topic on the integrated regeneration technology of either microwave/vacuum or microwave/ultrasonic was emphasised and explored for the future research and application of the oil vapor adsorption recovery technology.

  15. A controlled trial of the Litebook light-emitting diode (LED) light therapy device for treatment of Seasonal Affective Disorder (SAD)

    National Research Council Canada - National Science Library

    Desan, Paul H; Weinstein, Anea J; Michalak, Erin E; Tam, Edwin M; Meesters, Ybe; Ruiter, Martine J; Horn, Edward; Telner, John; Iskandar, Hani; Boivin, Diane B; Lam, Raymond W

    2007-01-01

    .... Light treatment devices using efficient light-emitting diodes (LEDs) whose output is relatively concentrated in short wavelengths may enable a more convenient effective therapy for Seasonal Affective Disorder (SAD). Methods...

  16. Integrated SiC Super Junction Transistor-Diode Devices for High-Power Motor Control ModulesOoperating at 500 C Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Monolithic Integrated SiC Super Junction Transistor-JBS diode (MIDSJT) devices are used to construct 500

  17. Diode laser (980nm) cartilage reshaping

    Science.gov (United States)

    El Kharbotly, A.; El Tayeb, T.; Mostafa, Y.; Hesham, I.

    2011-03-01

    Loss of facial or ear cartilage due to trauma or surgery is a major challenge to the otolaryngologists and plastic surgeons as the complicated geometric contours are difficult to be animated. Diode laser (980 nm) has been proven effective in reshaping and maintaining the new geometric shape achieved by laser. This study focused on determining the optimum laser parameters needed for cartilage reshaping with a controlled water cooling system. Harvested animal cartilages were angulated with different degrees and irradiated with different diode laser powers (980nm, 4x8mm spot size). The cartilage specimens were maintained in a deformation angle for two hours after irradiation then released for another two hours. They were serially measured and photographed. High-power Diode laser irradiation with water cooling is a cheep and effective method for reshaping the cartilage needed for reconstruction of difficult situations in otorhinolaryngologic surgery. Key words: cartilage,diode laser (980nm), reshaping.

  18. 100 years of the physics of diodes

    Science.gov (United States)

    Zhang, Peng; Valfells, Ágúst; Ang, L. K.; Luginsland, J. W.; Lau, Y. Y.

    2017-03-01

    The Child-Langmuir Law (CL), discovered a century ago, gives the maximum current that can be transported across a planar diode in the steady state. As a quintessential example of the impact of space charge shielding near a charged surface, it is central to the studies of high current diodes, such as high power microwave sources, vacuum microelectronics, electron and ion sources, and high current drivers used in high energy density physics experiments. CL remains a touchstone of fundamental sheath physics, including contemporary studies of nanoscale quantum diodes and nano gap based plasmonic devices. Its solid state analog is the Mott-Gurney law, governing the maximum charge injection in solids, such as organic materials and other dielectrics, which is important to energy devices, such as solar cells and light emitting diodes. This paper reviews the important advances in the physics of diodes since the discovery of CL, including virtual cathode formation and extension of CL to multiple dimensions, to the quantum regime, and to ultrafast processes. We review the influence of magnetic fields, multiple species in bipolar flow, electromagnetic and time dependent effects in both short pulse and high frequency THz limits, and single electron regimes. Transitions from various emission mechanisms (thermionic-, field-, and photoemission) to the space charge limited state (CL) will be addressed, especially highlighting the important simulation and experimental developments in selected contemporary areas of study. We stress the fundamental physical links between the physics of beams to limiting currents in other areas, such as low temperature plasmas, laser plasmas, and space propulsion.

  19. Au-controlled enhancement of photoluminescence of NiS nanostructures synthesized via a microwave-assisted hydrothermal technique

    CSIR Research Space (South Africa)

    Linganiso, EC

    2014-11-01

    Full Text Available Nickel sulphide (NiS) nanostructures decorated with gold (Au) nanoparticles (NPs) were synthesized via a microwave-assisted hydrothermal technique. Binary phase NiS (a and ß) crystalline nanostructures, bare, and decorated with Au NPs were obtained...

  20. MICROWAVE-ASSISTED SHAPE CONTROLLED BULK SYNTHESIS OF AG AND FE NANORODS IN POLY (ETHYLENE GLYCOL) SOLUTIONS

    Science.gov (United States)

    Bulk syntheses of silver (Ag) and iron (Fe) nanorods using poly (ethylene glycol), PEG, under microwave irradiation (MW) conditions are reported. Favorable conditions to make Ag nanorods were established and can be extended to make Fe nanorods with uniform size and shape. The nan...

  1. Controllable microwave and ultrasonic wave combined synthesis of ZnO micro-/nanostructures in HEPES solution and their shape-dependent photocatalytic activities

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qin; Li, Hui; Wang, Runming; Li, Guangfang; Yang, Hao [Key Laboratory for Green Chemical Process of Ministry of Education and Hubei Novel Reactor and Green Chemical Technology Key Laboratory, Wuhan Institute of Technology, Xiongchu Street, Wuhan 430073 (China); Chen, Rong, E-mail: rchenhku@hotmail.com [Key Laboratory for Green Chemical Process of Ministry of Education and Hubei Novel Reactor and Green Chemical Technology Key Laboratory, Wuhan Institute of Technology, Xiongchu Street, Wuhan 430073 (China); Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Lumo Road, Wuhan 430074 (China)

    2013-08-05

    Grahpical abstract: ZnO micro-/nanostructures with controllable size and morphology were successfully synthesized by microwave and ultrasonic wave combined method in HEPES solution, and exhibit shape-dependent photocatalytic activity for MB degradation under UV light irradiation. Highlights: •ZnO micro-/nanostructures were synthesized by combined microwave-ultrasonic wave method. •Morphologies of ZnO micro-/nanostructures could be modulated by varying reaction conditions. •HEPES plays a crucial role in the controllable synthesis of ZnO micro-/nanostructures. •ZnO micro-/nanostructures exhibit shape-dependent photocatalytic activity. •Spindle-like ZnO microstructures show superior photocatalytic activity. -- Abstract: Size- and morphology-controlled zinc oxide (ZnO) micro-/nanostructures have been successfully synthesized via a facile and rapid microwave and ultrasonic wave combined method in HEPES solution (HEPES = 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid). The as-prepared ZnO products are characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and UV–vis diffuse reflection spectroscopy (DRS). Various morphologies of ZnO products, including grenade-like, column-like, spindle-like, rod-like, shuttle-like and flower-like micro-/nanostructures are obtained, which are strongly dependent on Zn/HEPES moral ratio, pH value and Zn precursor. It is found that HEPES plays a crucial role in the formation of ZnO micro-/nanostructures with controllable size and morphology. The photocatalytic activities of the prepared ZnO micro-/nanostructures are evaluated by degradation of methylene blue (MB) under UV light irradiation, among which spindle-like ZnO microstructures exhibit superior photocatalytic activity compared with other ZnO products.

  2. Optically controllable dual-mode switching in single-mode Fabry-Pérot laser diode subject to one side-mode feedback and external single mode injection

    Science.gov (United States)

    Wu, Jian-Wei; Won, Yong Hyub

    2017-06-01

    In this paper, broadly tunable dual-mode lasing system is presented and demonstrated based on single-mode Fabry-Pérot laser diode subject to the feedback of one side mode amplified by an erbium-doped fiber amplifier in the external feedback cavity. The spacing between two resonance modes in output lasing spectrum is broadly tuned by introducing differently amplified side mode into the single-mode laser via the external cavity consisted of amplifier, filter, and polarization controller so that two difference frequencies of 1 THz and 0.6 THz are given to display the tunable behavior of dual-mode emission in this work. Therefore, under an external injection mode into the laser condition, the power dependent injection locking and optical bistability of generated dual-mode emission are discussed in detail. At different wavelength detunings, the emitted two resonance modes including the dominant and feedback modes are switched to on- or off-state by selecting proper high-low power level of the external injection mode. As a consequence, the maximum value of achieved dual-mode on-off ratio is as high as up to 45 dB.

  3. Improvement of Light Extraction Efficiency in Flip-Chip Light Emitting Diodes on SiC Substrate via Transparent Haze Films with Morphology-Controlled Collapsed Alumina Nanorods.

    Science.gov (United States)

    Baek, Seunghwa; Kang, Gumin; Shin, Dongheok; Bae, Kyuyoung; Kim, Yong Hyun; Kim, Kyoungsik

    2016-01-13

    We demonstrate GaN-based flip-chip light emitting diodes (FC-LEDs) on SiC substrate achieving high extraction efficiency by simply attaching the optically transparent haze films consisting of collapsed alumina nanorods. Through controlled etching time of alumina nanorods, we obtain four types of films that have different morphologies with different optical transmittance and haze properties. We show that the light output power of the FC-LEDs with film, which has 95.6% transmittance and 62.7% haze, increases by 20.4% in comparison to the bare LEDs. The angular radiation pattern of the LEDs also follows the Lambertian emission pattern without deteriorating the electrical properties of the device. The improvement of light extraction is mainly attributed to the reduced total internal reflection (TIR) via efficient out-coupling of guided light from SiC substrate to air by collapsed alumina nanorod structures in the film. The high transparency of film and reduced Fresnel reflection via graded refractive index transition between the film and SiC substrate also contribute to the extraction enhancement of the device. We systematically investigate the influence of haze film's geometrical or optical properties on the extraction efficiency of FC-LEDs, and this study will provide a novel approach to enhance the performance of various optoelectronic devices.

  4. Microwave Plasma Synthesis of Nanopowders

    Institute of Scientific and Technical Information of China (English)

    Joseph; Lik; Hang; Chau

    2007-01-01

    1 Results and Discussion Nanopowders were synthesized by using microwave plasma synthesis technique.The microwave plasma was operated in atmospheric pressure at a frequency of 2.45 GHz.The reaction temperature is directly related to the power of the microwave generator that can be controlled by adjusting the actual operating current.Firstly,ionization and dissociation of precursor species will be occurred in the plasma,nucleus can then be formed by the collision of these molecules,followed by the growth...

  5. Control Point Analysis comparison for 3 different treatment planning and delivery complexity levels using a commercial 3-dimensional diode array

    Energy Technology Data Exchange (ETDEWEB)

    Abdellatif, Ady, E-mail: ady.abdellatif@lhsc.on.ca [Department of Physics and Engineering, London Regional Cancer Program, London, Ontario (Canada); Gaede, Stewart [Department of Physics and Engineering, London Regional Cancer Program, London, Ontario (Canada); Department of Oncology, Western University, London, Ontario (Canada); Department of Medical Biophysics, Western University, London, Ontario (Canada)

    2014-07-01

    To investigate the use of “Control Point Analysis” (Sun Nuclear Corporation, Melbourne, FL) to analyze and compare delivered volumetric-modulated arc therapy (VMAT) plans for 3 different treatment planning complexity levels. A total of 30 patients were chosen and fully anonymized for the purpose of this study. Overall, 10 lung stereotactic body radiotherapy (SBRT), 10 head-and-neck (H and N), and 10 prostate VMAT plans were generated on Pinnacle{sup 3} and delivered on a Varian linear accelerator (LINAC). The delivered dose was measured using ArcCHECK (Sun Nuclear Corporation, Melbourne, FL). Each plan was analyzed using “Sun Nuclear Corporation (SNC) Patient 6” and “Control Point Analysis.” Gamma passing percentage was used to assess the differences between the measured and planned dose distributions and to assess the role of various control point binning combinations. Of the different sites considered, the prostate cases reported the highest gamma passing percentages calculated with “SNC Patient 6” (97.5% to 99.2% for the 3%, 3 mm) and “Control Point Analysis” (95.4% to 98.3% for the 3%, 3 mm). The mean percentage of passing control point sectors for the prostate cases increased from 51.8 ± 7.8% for individual control points to 70.6 ± 10.5% for 5 control points binned together to 87.8 ± 11.0% for 10 control points binned together (2%, 2-mm passing criteria). Overall, there was an increasing trend in the percentage of sectors passing gamma analysis with an increase in the number of control points binned together in a sector for both the gamma passing criteria (2%, 2 mm and 3%, 3 mm). Although many plans passed the clinical quality assurance criteria, plans involving the delivery of high Monitor Unit (MU)/control point (SBRT) and plans involving high degree of modulation (H and N) showed less delivery accuracy per control point compared with plans with low MU/control point and low degree of modulation (prostate)

  6. Mixing of 10-microm radiation in room-temperature Schottky diodes.

    Science.gov (United States)

    Tannenwald, P E; Fetterman, H R; Freed, C; Parker, C D; Clifton, B J; O'Donnell, R G

    1981-10-01

    Schottky diodes have been used as room-temperature mixers of CO(2)-laser radiation. When a microwave local oscillator signal was introduced directly into the diode, beat notes between lasers separated by up to 69 GHz were observed. At CO(2) frequencies (30 THz) the photon energy exceeds the measured dc nonlinearities, and the device is expected to approach operation as a photon counter rather than a classical resistive mixer.

  7. Powerful infrared emitting diodes

    Directory of Open Access Journals (Sweden)

    Kogan L. M.

    2012-02-01

    Full Text Available Powerful infrared LEDs with emission wavelength 805 ± 10, 870 ± 20 and 940 ± 10 nm developed at SPC OED "OPTEL" are presented in the article. The radiant intensity of beam diode is under 4 W/sr in the continuous mode and under 100 W/sr in the pulse mode. The radiation power of wide-angle LEDs reaches 1 W in continuous mode. The external quantum efficiency of emission IR diodes runs up to 30%. There also has been created infrared diode modules with a block of flat Fresnel lenses with radiant intensity under 70 W/sr.

  8. A randomized controlled study for the treatment of acne vulgaris using high-intensity 414 nm solid state diode arrays.

    Science.gov (United States)

    Ash, Caerwyn; Harrison, Anna; Drew, Samantha; Whittall, Rebecca

    2015-01-01

    The treatment of acne vulgaris poses a challenge to the dermatologist, and the disease causes emotional anxiety for the patient. The treatment of acne vulgaris may be well-suited to home-use applications, where sufferers may be too embarrassed to seek medical treatment. This randomized controlled study is designed to quantify the effectiveness of using a blue light device in a therapy combined with proprietary creams, in the investigation of a self-treatment regimen. A total of 41 adults with mild-to-moderate facial inflammatory acne were recruited. The subjects were randomly assigned to combination blue light therapy (n = 26) or control (n = 15). Photography was used for qualitative assessment of lesion counts, at weeks 1, 2, 4, 8, and 12. All subjects in the treatment cohort achieved a reduction in their inflammatory lesion counts after 12 weeks. The mean inflammatory lesion counts reduced by 50.02% in the treatment cohort, and increased by 2.45% in the control cohort. The reduction in inflammatory lesions was typically observable at week-3, and maximal between weeks 8 and 12. The treatment is free of pain and side-effects. The blue light device offers a valuable alternative to antibiotics and potentially irritating topical treatments. Blue light phototherapy, using a narrow-band LED light source, appears to be a safe and effective additional therapy for mild to moderate acne.

  9. Lightweight NiFe2O4 with controllable 3D network structure and enhanced microwave absorbing properties

    Science.gov (United States)

    Wang, Fen; Wang, Xing; Zhu, Jianfeng; Yang, Haibo; Kong, Xingang; Liu, Xiao

    2016-11-01

    3D network structure NiFe2O4 was successfully synthesized by a templated salt precipitation method using PMMA colloid crystal as templates. The morphology, phase composition and microwave absorbing properties of as-prepared samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), vector network analyzer (VNA), and so on. The results revealed that the 3D network structure was configurated with smooth spherical walls composed of NiFe2O4 nanocrystals and their pore diameters being in the range of 80–250 nm. The microwave absorption properties of the 3D network structure NiFe2O4 were crucially determined by the special structure. The synergy of intrinsic magnetic loss of magnetic NiFe2O4 and the interfacial polarization enhanced by 3D network structure and the interaction of multiple mechanisms endowed the sample with the feature of strong absorption, broad bandwidth and lightweight. There is more than one valley in the reflection loss curves and the maximum reflection loss is 27.5 dB with a bandwidth of 4 GHz. Moreover, the 3D network structure NiFe2O4 show a greater reflection loss with the same thickness comparing to the ordinary NiFe2O4 nanoparticles, which could achieve the feature of lightweight of the microwave absorbing materials.

  10. Offset phase locking of noisy diode lasers aided by frequency division

    Science.gov (United States)

    Ivanov, E. N.; Esnault, F.-X.; Donley, E. A.

    2011-08-01

    For heterodyne phase locking, frequency division of the beat note between two oscillators can improve the reliability of the phase lock and the quality of the phase synchronization. Frequency division can also reduce the size, weight, power, and cost of the instrument by excluding the microwave synthesizer from the control loop when the heterodyne offset frequency is large (5 to 10 GHz). We have experimentally tested the use of a frequency divider in an optical phase-lock loop and compared the achieved level of residual phase fluctuations between two diode lasers with that achieved without the use of a frequency divider. The two methods achieve comparable phase stability provided that sufficient loop gain is maintained after frequency division to preserve the required bandwidth. We have also numerically analyzed the noise properties and internal dynamics of phase-locked loops subjected to a high level of phase fluctuations, and our modeling confirms the expected benefits of having an in-loop frequency divider.

  11. Detonation control

    Science.gov (United States)

    Mace, Jonathan L.; Seitz, Gerald J.; Bronisz, Lawrence E.

    2016-10-25

    Detonation control modules and detonation control circuits are provided herein. A trigger input signal can cause a detonation control module to trigger a detonator. A detonation control module can include a timing circuit, a light-producing diode such as a laser diode, an optically triggered diode, and a high-voltage capacitor. The trigger input signal can activate the timing circuit. The timing circuit can control activation of the light-producing diode. Activation of the light-producing diode illuminates and activates the optically triggered diode. The optically triggered diode can be coupled between the high-voltage capacitor and the detonator. Activation of the optically triggered diode causes a power pulse to be released from the high-voltage capacitor that triggers the detonator.

  12. Terahertz pulse detection by the GaAs Schottky diodes

    Science.gov (United States)

    Laperashvili, Tina; Kvitsiani, Orest; Imerlishvili, Ilia; Laperashvili, David

    2010-06-01

    We present the results of experimental studies of physical properties of the detection process of GaAs Schottky diodes for terahertz frequency radiation. The development of technology in the THz frequency band has a rapid progress recently. Considered as an extension of the microwave and millimeter wave bands, the THz frequency offers greater communication bandwidth than is available at microwave frequencies. The Schottky barrier contact has an important role in the operation of many GaAs devices. GaAs Schottky diodes have been the primary nonlinear device used in millimeter and sub millimeter wave detectors and receivers. GaAs Schottky diodes are especially interesting due to their high mobility transport characteristics, which allows for a large reduction of the resistance-capacitance (RC) time constant and thermal noise. In This work are investigated the electrical and photoelectric properties of GaAs Schottky diodes. Samples were obtained by deposition of different metals (Au, Ni, Pt, Pd, Fe, In, Ga, Al) on semiconductor. For fabrication metal-semiconductor (MS) structures is used original method of metal electrodepositing. In this method electrochemical etching of semiconductor surface occurs just before deposition of metal from the solution, which contains etching material and metal ions together. For that, semiconductor surface cleaning processes and metal deposition carries out in the same technological process. In the experiments as the electrolyte was used aqueous solution of chlorides. Metal deposition was carried out at room temperature.

  13. Microwave power engineering applications

    CERN Document Server

    Okress, Ernest C

    2013-01-01

    Microwave Power Engineering, Volume 2: Applications introduces the electronics technology of microwave power and its applications. This technology emphasizes microwave electronics for direct power utilization and transmission purposes. This volume presents the accomplishments with respect to components, systems, and applications and their prevailing limitations in the light of knowledge of the microwave power technology. The applications discussed include the microwave heating and other processes of materials, which utilize the magnetron predominantly. Other applications include microwave ioni

  14. Advances in microwaves 8

    CERN Document Server

    Young, Leo

    2013-01-01

    Advances in Microwaves, Volume 8 covers the developments in the study of microwaves. The book discusses the circuit forms for microwave integrated circuits; the analysis of microstrip transmission lines; and the use of lumped elements in microwave integrated circuits. The text also describes the microwave properties of ferrimagnetic materials, as well as their interaction with electromagnetic waves propagating in bounded waveguiding structures. The integration techniques useful at high frequencies; material technology for microwave integrated circuits; specific requirements on technology for d

  15. Chemically Modulated Graphene Diodes

    OpenAIRE

    Kim, Hye-young; Lee, Kangho; McEvoy, Niall; Yim, Chanyoung; Duesberg, Georg S.

    2013-01-01

    PUBLISHED We report the manufacture of novel graphene diode sensors (GDS), which are composed of monolayer graphene on silicon substrates, allowing exposure to liquids and gases. Parameter changes in the diode can be correlated with charge transfer from various adsorbates. The GDS allows for investigation and tuning of extrinsic doping of graphene with great reliability. The demonstrated recovery and long-term stability qualifies the GDS as a new platform for gas, environmental, and biocom...

  16. Indocyanine green-augmented diode laser therapy vs. long-pulsed Nd:YAG (1064 nm) laser treatment of telangiectatic leg veins: a randomized controlled trial.

    Science.gov (United States)

    Klein, A; Buschmann, M; Babilas, P; Landthaler, M; Bäumler, W

    2013-08-01

    Telangiectatic leg veins (TLV) represent a common cosmetic problem. Near infrared lasers have been widely used in treatment because of their deeper penetration into the dermis, but with varying degrees of success, particularly because of different vessel diameters. Indocyanine green (ICG)-augmented diode laser treatment (ICG+DL) may present an alternative treatment option. This trial evaluates the efficacy of ICG+DL in the treatment of TLV and compares the safety and efficacy of therapy with the standard treatment, the long-pulsed neodymium-doped yttrium aluminium garnet (Nd:YAG) laser. In a prospective randomized controlled clinical trial, 29 study participants with TLV were treated with a Nd:YAG laser (λem = 1064 nm, 160-240 J cm(-2) , 65-ms pulse duration, 5-mm spot size) and ICG+DL (λem = 810 nm, 60-110 J cm(-2) , 48-87-ms pulse duration, 6-mm spot size; total ICG dose 4 mg kg(-1) ) in a side-by-side comparison in one single treatment setting that included histological examination in four participants. Two blinded investigators and the participants assessed clearance rate, cosmetic appearance and adverse events up to 3 months after treatment. According to both the investigators' and participants' assessment, clearance rates were significantly better after ICG+DL therapy than after Nd:YAG laser treatment (P treatment, participants rated ICG+DL therapy to be more painful (6·1 ± 2·0) than Nd:YAG laser (5·4 ± 2·0). ICG+DL therapy represents a new and promising treatment modality for TLV, with high clearance rates and a very good cosmetic outcome after one single treatment session. © 2013 British Association of Dermatologists.

  17. A controlled trial of the Litebook light-emitting diode (LED light therapy device for treatment of Seasonal Affective Disorder (SAD

    Directory of Open Access Journals (Sweden)

    Telner John

    2007-08-01

    Full Text Available Abstract Background Recent research has emphasized that the human circadian rhythm system is differentially sensitive to short wavelength light. Light treatment devices using efficient light-emitting diodes (LEDs whose output is relatively concentrated in short wavelengths may enable a more convenient effective therapy for Seasonal Affective Disorder (SAD. Methods The efficacy of a LED light therapy device in the treatment of SAD was tested in a randomized, double-blind, placebo-controlled, multi-center trial. Participants aged 18 to 65 with SAD (DSM-IV major depression with seasonal pattern were seen at Baseline and Randomization visits separated by 1 week, and after 1, 2, 3 and 4 weeks of treatment. Hamilton Depression Rating Scale scores (SIGH-SAD were obtained at each visit. Participants with SIGH-SAD of 20 or greater at Baseline and Randomization visits were randomized to active or control treatment: exposure to the Litebook LED treatment device (The Litebook Company Ltd., Alberta, Canada which delivers 1,350 lux white light (with spectral emission peaks at 464 nm and 564 nm at a distance of 20 inches or to an inactivated negative ion generator at a distance of 20 inches, for 30 minutes a day upon awakening and prior to 8 A.M. Results Of the 26 participants randomized, 23 completed the trial. Mean group SIGH-SAD scores did not differ significantly at randomization. At trial end, the proportions of participants in remission (SIGH-SAD less than 9 were significantly greater (Fisher's exact test, and SIGH-SAD scores, as percent individual score at randomization, were significantly lower (t-test, with active treatment than with control, both in an intent-to-treat analysis and an observed cases analysis. A longitudinal repeated measures ANOVA analysis of SIGH-SAD scores also indicated a significant interaction of time and treatment, showing superiority of the Litebook over the placebo condition. Conclusion The results of this pilot study support

  18. Estimating p-n Diode Bulk Parameters, Bandgap Energy and Absolute Zero by a Simple Experiment

    Science.gov (United States)

    Ocaya, R. O.; Dejene, F. B.

    2007-01-01

    This paper presents a straightforward but interesting experimental method for p-n diode characterization. The method differs substantially from many approaches in diode characterization by offering much tighter control over the temperature and current variables. The method allows the determination of important diode constants such as temperature…

  19. Effects of Light-Emitting Diode Therapy on Muscle Hypertrophy, Gene Expression, Performance, Damage, and Delayed-Onset Muscle Soreness: Case-control Study with a Pair of Identical Twins.

    Science.gov (United States)

    Ferraresi, Cleber; Bertucci, Danilo; Schiavinato, Josiane; Reiff, Rodrigo; Araújo, Amélia; Panepucci, Rodrigo; Matheucci, Euclides; Cunha, Anderson Ferreira; Arakelian, Vivian Maria; Hamblin, Michael R; Parizotto, Nivaldo; Bagnato, Vanderlei

    2016-10-01

    The aim of this study was to verify how a pair of monozygotic twins would respond to light-emitting diode therapy (LEDT) or placebo combined with a strength-training program during 12 weeks. This case-control study enrolled a pair of male monozygotic twins, allocated randomly to LEDT or placebo therapies. Light-emitting diode therapy or placebo was applied from a flexible light-emitting diode array (λ = 850 nm, total energy = 75 J, t = 15 seconds) to both quadriceps femoris muscles of each twin immediately after each strength training session (3 times/wk for 12 weeks) consisting of leg press and leg extension exercises with load of 80% and 50% of the 1-repetition maximum test, respectively. Muscle biopsies, magnetic resonance imaging, maximal load, and fatigue resistance tests were conducted before and after the training program to assess gene expression, muscle hypertrophy and performance, respectively. Creatine kinase levels in blood and visual analog scale assessed muscle damage and delayed-onset muscle soreness, respectively, during the training program. Compared with placebo, LEDT increased the maximal load in exercise and reduced fatigue, creatine kinase, and visual analog scale. Gene expression analyses showed decreases in markers of inflammation (interleukin 1β) and muscle atrophy (myostatin) with LEDT. Protein synthesis (mammalian target of rapamycin) and oxidative stress defense (SOD2 [mitochondrial superoxide dismutase]) were up-regulated with LEDT, together with increases in thigh muscle hypertrophy. Light-emitting diode therapy can be useful to reduce muscle damage, pain, and atrophy, as well as to increase muscle mass, recovery, and athletic performance in rehabilitation programs and sports medicine.

  20. THE CONTROL ALGORITHM OF THE DRYING PROCESS PARTICULATE MATERIALS IN THE APPARATUS WITH THE SWIRLING FLOW OF COOLANT AND MICROWAVE ENERGY SUPPLY

    Directory of Open Access Journals (Sweden)

    S. T. Antipov

    2015-01-01

    Full Text Available The technical task of the process is to improve the drying quality of the final product, increasing the precision and reliability of control, the reduction of specific energy consumption. One of the ways to improve the process is complex and i ts local automation. This paper deals with the problems of development and creation of a new control algorithm drying process of the particulate material. Identified a number of shortcomings of the existing methods of automatic control of the process. As a result, the authors proposed a method for drying particulate materials in the device with swirling flow and the microwave energy supply and its automatic control algorithm. The description of the operating principle of the drying apparatus consists in that the particulate material is wet by using a tangential flow of coolant supplied to the cylinder-drying apparatus which also serves the axial coolant flow, whereby the heat transfer fluid with the particulate material begins to undergo a complex circular movement along the circumference apparatus, thereby increasing its speed and its operation control algorithm. The work of this scheme is carried out at three levels of regulation on the basis of determining the coefficient of efficiency of the dryer, which makes it possible to determine the optimal value of the power equipment and to forecast the cost of electricity. All of the above allows you to get ready for a high quality product while minimizing thermal energy and material costs by optimizing the operating parameters of the drying of the particulate material in the dryer with a combined microwave energy supply and ensure the rational use of heat energy by varying their quantity depending on the characteristics to be dried particulate material and the course of the process.

  1. Nonsurgical periodontal therapy with/without diode laser modulates metabolic control of type 2 diabetics with periodontitis: a randomized clinical trial

    NARCIS (Netherlands)

    Koçak, E.; Sağlam, M.; Kayış, S.A.; Dündar, N.; Kebapçılar, L.; Loos, B.G.; Hakki, S.S.

    2016-01-01

    In order to evaluate whether nonsurgical periodontal treatment with/without diode laser (DL) decontamination improves clinical parameters, the levels of IL-1β, IL-6, IL-8, intercellular adhesion molecule (ICAM), and vascular cell adhesion molecule (VCAM) in gingival crevicular fluid and metabolic co

  2. Nonsurgical periodontal therapy with/without diode laser modulates metabolic control of type 2 diabetics with periodontitis: a randomized clinical trial

    NARCIS (Netherlands)

    Koçak, E.; Sağlam, M.; Kayış, S.A.; Dündar, N.; Kebapçılar, L.; Loos, B.G.; Hakki, S.S.

    2016-01-01

    In order to evaluate whether nonsurgical periodontal treatment with/without diode laser (DL) decontamination improves clinical parameters, the levels of IL-1β, IL-6, IL-8, intercellular adhesion molecule (ICAM), and vascular cell adhesion molecule (VCAM) in gingival crevicular fluid and metabolic

  3. A novel method for stoichiometric reduction of (U3O8,PuO2) and its controlled oxidation using microwave

    Science.gov (United States)

    Singh, G.; Kumar, Pradeep; Aher, S.; Purohit, P.; Khot, P. M.; Prakash, Amrit; Das, D. K.; Behere, P. G.; Afzal, Mohd

    2016-10-01

    We report a process for stoichiometric reduction of U3O8 and (U3O8,PuO2) mixed oxide powders using an indigenously developed 2.4 GHz microwave processing system. The process parameters were optimized by interpreting reduction kinetic curves at a temperature which is 150 °C lower than the conventional reduction. The process improved the sinterability of the powder which was evaluated in terms of average particle size, BET specific surface area and bulk density. A quick method for controlled oxidation of the reduced powder to incorporate a controlled amount of hyper-stoichiometry was demonstrated by modifying the same reduction process. The percent reduction was measured experimentally using O:(U + Pu) ratio. The X-ray diffraction analysis confirmed the various phases present. The process is novel considering shorter processing cycle, lower temperature processing, improved powder properties, energy efficiency and cost effectiveness.

  4. Study of federal microwave standards

    Energy Technology Data Exchange (ETDEWEB)

    David, L.

    1980-08-01

    Present and future federal regulatory processes which may impact the permissible levels of microwave radiation emitted by the SPS Microwave Power Transmission (MPTS) were studied. An historical development of US occupational and public microwave standards includes an overview of Western and East European philosophies of environmental protection and neurophysiology which have led to the current widely differing maximum permissible exposure limits to microwaves. The possible convergence of microwave standards is characterized by a lowering of Western exposure levels while Eastern countries consider standard relaxation. A trend toward stricter controls on activities perceived as harmful to public health is under way as is interest in improving the federal regulatory process. Particularly relevant to SPS is the initiation of long-term, low-level microwave exposure programs. Coupled with new developments in instrumentation and dosimetry, the results from chronic exposure program and population exposure studies could be expected within the next five to ten years. Also discussed is the increasing public concern that rf energy is yet another hazardous environmental agent.

  5. Controlled synthesis of CdSe quantum dots by a microwave-enhanced process: a green approach for mass production.

    Science.gov (United States)

    Ayele, Delele Worku; Chen, Hung-Ming; Su, Wei-Nien; Pan, Chun-Jern; Chen, Liang-Yih; Chou, Hung-Lung; Cheng, Ju-Hsiang; Hwang, Bing-Joe; Lee, Jyh-Fu

    2011-05-09

    A method that does not employ hot-injection techniques has been developed for the size-tunable synthesis of high-quality CdSe quantum dots (QDs) with zinc blende structure. In this environmentally benign synthetic route, which uses less toxic precursors, solvents, and capping ligands, CdSe QDs that absorb visible light are obtained. The size of the as-prepared CdSe QDs and thus their optical properties can be manipulated by changing the microwave reaction conditions. The QDs were characterized by XRD, TEM, UV/Vis, FTIR, time-resolved fluorescence spectroscopy, and fluorescence spectrophotometry. In this approach, the reaction is conducted in open air and at a much lower temperature than in hot-injection techniques. The use of microwaves in this process allows for a highly reproducible and effective synthesis protocol that is fully adaptable for mass production and can be easily employed to synthesize a variety of semiconductor QDs with the desired properties. Possible applications of the CdSe QDs were assessed by deposition on TiO(2) films.

  6. Directed and diode percolation

    Science.gov (United States)

    Redner, S.

    1982-03-01

    We study the novel percolation phenomena that occur in random-lattice networks consisting of resistor-like and diode-like bonds. Resistor bonds connect or "transmit information" in either direction along their length, while diodes connect in one direction only. We first treat the special case of directed bond percolation, in which the diodes are aligned along a preferred axis. Mean-field theory shows that clusters become extremely anisotropic near the percolation transition and that their shapes are characterized by two correlation lengths, one parallel and one transverse to the preferred axis. These lengths diverge with exponents ν∥=1 and ν⊥=12, respectively, from which we can show that the upper critical dimension for this system must be five. We also treat a more general random network on the square lattice containing resistors and diodes of arbitrary orientation. Duality arguments are applied to obtain exact results for the location of phase transitions in this system. We then use a position-space renormalization-group approach to map out the phase diagram and calculate critical exponents. This system has an isotropic percolating phase, and phases which percolate in only one direction. Novel types of transitions occur between these phases, in which the diode orientation plays a fundamental role. These percolating phases meet with the nonpercolating phase along a line of multicritical points, where concentration and orientational fluctuations are simultaneously critical.

  7. Effects of increased microwave heating power in the stellarator TJ-K

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, Alejandro; Koehn, Alf; Ali, Ahmed; Ramisch, Mirko [Institute of Interfacial Process Engineering and Plasma Technology, University of Stuttgart, Stuttgart (Germany)

    2015-05-01

    One of the microwave heating systems at the stellarator TJ-K has been recently upgraded: a third klystron has been installed, increasing the heating power from 4 kW to 6 kW operating at 14 GHz. A phased-array antenna is used which allows to vary the injection angle by sweeping the microwave frequency in order control the coupling mechanism of the microwave to the plasma. With the two klystrons already installed, ionization degrees of α ≅ 1 have been reached. We expect that an increased heating power, by means of the third klystron put into operation, leads to an increase in the electron temperature T{sub e} only, rather than in electron density n{sub e}, and thus a decrease in the collision frequency ν{sub ei} ∝ n{sub e}T{sub e}{sup -3/2} which has an impact on heating flow damping and neoclassical properties. Parameter scans have been performed in order to characterize the new heating scenario. A radial movable Langmuir probe has been used to obtain radial profiles of the electron density and temperature. An arrangement of bolometers and an optical diode have been used to obtain the power losses by radiation. A particle and power balance model is used to obtain estimated densities and temperatures in order to compare with the experimental results.

  8. Embedded solution for a microwave moisture meter

    Science.gov (United States)

    In this paper, the conversion of a PC or laptop-controlled microwave moisture meter to a stand-alone meter hosting its own embedded system is discussed. The moisture meter is based on the free-space transmission measurement technique and uses low-intensity microwaves to measure the attenuation and p...

  9. Tunable Water-based Microwave Metasurface

    DEFF Research Database (Denmark)

    Kapitanova, Polina; Odit, Mikhail; Dobrykh, Dmitry

    2017-01-01

    A water-based dynamically tunable microwave metasurface is developed and experimentally investigated. A simple approach to tune the metasurface properties by changing the shape of water-based unit cells by gravitation force is proposed. The transmission spectra of the metasurface for linear...... angle. The proposed approach can be used to design cheap metasurfaces for electromagnetic wave control in the microwave frequency range....

  10. Drivers for High Power Laser Diodes

    Institute of Scientific and Technical Information of China (English)

    Yankov P; Todorov D; Saramov E

    2006-01-01

    During the last year the high power laser diodes jumped over the 1 kW level of CW power for a stack,and the commercial 1 cm bars reached 100 W output optical power at the standard wavelengths around 800 nm and 980 nm. The prices are reaching the industry acceptable levels. All Nd:YAG and fiber industrial lasers manufacturers have developed kW prototypes. Those achievements have set new requirements for the power supplies manufactuers-high and stable output current, and possibilities for fast control of the driving current, keeping safe the expensive laser diode. The fast switching frequencies also allow long range free space communications and optical range finding. The high frequencies allow the design of a 3D laser radar with high resolution and other military applications. The prospects for direct laser diode micro machining are also attractive.

  11. Deterministic polarization chaos from a laser diode

    CERN Document Server

    Virte, Martin; Thienpont, Hugo; Sciamanna, Marc

    2014-01-01

    Fifty years after the invention of the laser diode and fourty years after the report of the butterfly effect - i.e. the unpredictability of deterministic chaos, it is said that a laser diode behaves like a damped nonlinear oscillator. Hence no chaos can be generated unless with additional forcing or parameter modulation. Here we report the first counter-example of a free-running laser diode generating chaos. The underlying physics is a nonlinear coupling between two elliptically polarized modes in a vertical-cavity surface-emitting laser. We identify chaos in experimental time-series and show theoretically the bifurcations leading to single- and double-scroll attractors with characteristics similar to Lorenz chaos. The reported polarization chaos resembles at first sight a noise-driven mode hopping but shows opposite statistical properties. Our findings open up new research areas that combine the high speed performances of microcavity lasers with controllable and integrated sources of optical chaos.

  12. A CW Gunn Diode Switching Element.

    Science.gov (United States)

    Hurtado, Marco; Rosenbaum, Fred J.

    As part of a study of the application of communication satellites to educational development, certain technical aspects of such a system were examined. A current controlled bistable switching element using a CW Gunn diode is reported on here. With modest circuits switching rates of the order of 10 MHz have been obtained. Switching is initiated by…

  13. A CW Gunn diode bistable switching element.

    Science.gov (United States)

    Hurtado, M.; Rosenbaum, F. J.

    1972-01-01

    Experiments with a current-controlled bistable switching element using a CW Gunn diode are reported. Switching rates of the order of 10 MHz have been obtained. Switching is initiated by current pulses of short duration (5-10 ns). Rise times of the order of several nanoseconds could be obtained.

  14. Comparative evaluation of diode laser versus argon laser photocoagulation in patients with central serous retinopathy: A pilot, randomized controlled trial [ISRCTN84128484

    Directory of Open Access Journals (Sweden)

    Venkatesh Pradeep

    2004-10-01

    Full Text Available Abstract Background To evaluate the efficacy of diode laser photocoagulation in patients with central serous retinopathy (CSR and to compare it with the effects of argon green laser. Methods Thirty patients with type 1 unilateral CSR were enrolled and evaluated on parameters like best corrected visual acuity (BCVA, direct and indirect ophthalmoscopy, amsler grid for recording scotoma and metamorphopsia, contrast sensitivity using Cambridge low contrast gratings and fluorescein angiography to determine the site of leakage. Patients were randomly assigned into 2 groups according to the statistical random table using sequence generation. In Group 1 (n = 15, diode laser (810 nm photocoagulation was performed at the site of leakage while in Group 2 (n = 15, eyes were treated with argon green laser (514 nm using the same laser parameters. Patients were followed up at 4, 8 and 12 weeks after laser. Results The mean BCVA in group 1 improved from a pre-laser decimal value of 0.29 ± 0.14 to 0.84 ± 0.23 at 4 weeks and 1.06 ± 0.09 at 12 weeks following laser. In group 2, the same improved from 0.32 ± 0.16 to 0.67 ± 0.18 at 4 weeks and 0.98 ± 0.14 at 12 weeks following laser. The improvement in BCVA was significantly better in group 1 (p Conclusion Diode laser may be a better alternative to argon green laser whenever laser treatment becomes indicated in patients with central serous retinopathy in terms of faster visual rehabilitation and better contrast sensitivity. In addition, diode laser also has the well-recognized ergonomic and economic advantages.

  15. Microwave Activation of Drug Release

    DEFF Research Database (Denmark)

    Jónasson, Sævar Þór

    Due to current limitations in control of pharmaceutical drug release in the body along with increasing medicine use, methods of externally-controlled drug release are of high interest. In this thesis, the use of microwaves is proposed as a technique with the purpose of externally activating...... setup, called the microwave activation system has been developed and tested on a body phantom that emulates the human torso. The system presented in this thesis, operates unobtrusively, i.e. without physically interfering with the target (patient). The torso phantom is a simple dual-layered cylindrical...... the phantom is of interest for disclosing essential information about the limitations of the concept, the phantom and the system. For these purposes, a twofold operation of the microwave activation system was performed, which are reciprocal of each other. In the first operation phase, named mapping...

  16. Terminal area automatic navigation, guidance, and control research using the Microwave Landing System (MLS). Part 2: RNAV/MLS transition problems for aircraft

    Science.gov (United States)

    Pines, S.

    1982-01-01

    The problems in navigation and guidance encountered by aircraft in the initial transition period in changing from distance measuring equipment, VORTAC, and barometric instruments to the more precise microwave landing system data type navaids in the terminal area are investigated. The effects of the resulting discontinuities on the estimates of position and velocity for both optimal (Kalman type navigation schemes) and fixed gain (complementary type) navigation filters, and the effects of the errors in cross track, track angle, and altitude on the guidance equation and control commands during the critical landing phase are discussed. A method is presented to remove the discontinuities from the navigation loop and to reconstruct an RNAV path designed to land the aircraft with minimal turns and altitude changes.

  17. Solid-state pulsed microwave bridge for electron spin echo spectrometers of 8-mm wavelength range

    Directory of Open Access Journals (Sweden)

    Kalabukhova E. N.

    2012-12-01

    Full Text Available The article presents a construction of a coherent pulsed microwave bridge with an output power up to 10 Wt with a time resolution of 10–8 seconds at a pulse repetition rate of 1 kHz designed for electron spin echo spectrometers. The bridge is built on a homodyne scheme based on IMPATT diodes, which are used for modulation and amplification of microwave power coming from the reference Gunn diode oscillator. The advantages of the bridge are optimal power and minimum pulse width, simple operation, low cost.

  18. Amplitude-stabilized frequency-modulated laser diode and its interferometric sensing applications.

    Science.gov (United States)

    Takahashi, Y; Yoshino, T; Ohde, N

    1997-08-20

    A direct frequency-modulated (FM) laser diode light source without light power variation is developed. The amplitude variation of the FM laser diode is compensated by means of a feedback system with use of a superluminescent diode as an external light power controller. Output power greater than 1 mW is obtained at the modulation frequency to 5 kHz with a >10 stabilization factor. By use of the amplitude-stabilized FM laser diode, we measured subfringes with high accuracy in FM continuous wave interferometry, increased the dynamic range of the displacement measurement, and improved the stabilization factor in the laser diode feedback interferometer.

  19. Photonic microwave generation with high-power photodiodes

    CERN Document Server

    Fortier, Tara M; Hati, Archita; Nelson, Craig; Taylor, Jennifer A; Fu, Yang; Campbell, Joe; Diddams, Scott A

    2013-01-01

    We utilize and characterize high-power, high-linearity modified uni-traveling carrier (MUTC) photodiodes for low-phase-noise photonic microwave generation based on optical frequency division. When illuminated with picosecond pulses from a repetition-rate-multiplied gigahertz Ti:sapphire modelocked laser, the photodiodes can achieve 10 GHz signal power of +14 dBm. Using these diodes, a 10 GHz microwave tone is generated with less than 500 attoseconds absolute integrated timing jitter (1 Hz-10 MHz) and a phase noise floor of -177 dBc/Hz. We also characterize the electrical response, amplitude-to-phase conversion, saturation and residual noise of the MUTC photodiodes.

  20. Au-controlled enhancement of photoluminescence of NiS nanostructures synthesized via a microwave-assisted hydrothermal technique

    Energy Technology Data Exchange (ETDEWEB)

    Linganiso, Ella Cebisa [DST/CSIR Nanotech Innovation Centre, National Centre for Nano-structured Materials, Council for Scientific and Industrial Research, PO Box 395, Pretoria 0001 (South Africa); Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, Wits, 2050 Johannesburg (South Africa); Mwakikunga, Bonex Wakufwa, E-mail: bmwakikunga@csir.co.za [DST/CSIR Nanotech Innovation Centre, National Centre for Nano-structured Materials, Council for Scientific and Industrial Research, PO Box 395, Pretoria 0001 (South Africa); Department of Physics and Biochemical Sciences, The Polytechnic of the University of Malawi, Private Bag 303, Chichiri, Blantyre 0003 (Malawi); Mhlanga, Sabelo Dalton [Department of Applied Chemistry, University of Johannesburg, PO Box 17011, Doornfontein, 2028 Johannesburg (South Africa); Coville, Neil John [Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, Wits, 2050 Johannesburg (South Africa); DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, Private Bag 3, Wits, 2050 Johannesburg (South Africa)

    2014-11-15

    Nickel sulphide (NiS) nanostructures decorated with gold (Au) nanoparticles (NPs) were synthesized via a microwave-assisted hydrothermal technique. Binary phase NiS (α and β) crystalline nanostructures, bare, and decorated with Au NPs were obtained and confirmed by X-ray diffraction (XRD) studies. TEM analysis revealed that the NiS nanostructures were of various shapes. A quantum confinement effect was confirmed by the blue shift PL emissions and high optical energy band gap observed for the as-synthesized sample. A threefold light emission enhancement due to Au NP coatings was obtained when Au metal NP decoration concentrations was varied from 1% to 10%. These enhancements were attributed to the surface plasmon resonance (SPR) excitation of the surface decorated metal NPs which results in an increased rate of spontaneous emission. The PL enhancement factor was observed to vary at different NiS emissions as well as with the size of the Au NPs. The effect of metal NP decoration on the PL emission of NiS is to the best of our knowledge, presented for the first time. - Highlights: • Binary phase NiS decorated with gold nanoparticles. • Quantum confinement effect confirmed by PL analysis. • PL enhancement depending more on particle size distribution. • Effect of gold on NiS PL is to the best of our knowledge reported for the first time.

  1. CoxNi100-x nanoparticles encapsulated by curved graphite layers: controlled in situ metal-catalytic preparation and broadband microwave absorption

    Science.gov (United States)

    Wang, H.; Dai, Y. Y.; Geng, D. Y.; Ma, S.; Li, D.; An, J.; He, J.; Liu, W.; Zhang, Z. D.

    2015-10-01

    We report a one-step approach for preparing dispersive CoxNi100-x nanoparticles completely encapsulated by curved graphite layers. The nanoparticles were prepared by evaporating Co-Ni alloys and the shell of graphite layers was formed by in situ metal-catalytic growth on the surface of nanoparticles whose layer number was controlled by tuning the Co content of the alloys. By modulating the composition of the magnetic core and the layer number of the shell, the magnetic and dielectric properties of these core/shell structures are simultaneously optimized and their permeability and permittivity were improved to obtain the enhanced electromagnetic match. As a result, the bandwidth of reflection loss (RL) exceeding -20 dB (99% absorption) of the nanocapsules is 9.6 GHz for S1, 12.8 GHz for S2, 13.5 GHz for S3 and 14.2 GHz for S4. The optimal RL value reaches -53 dB at 13.2 GHz for an absorber thickness of 2.55 mm. An optimized impedance match by controlling the growth of the core and shell is responsible for this extraordinary microwave absorption.We report a one-step approach for preparing dispersive CoxNi100-x nanoparticles completely encapsulated by curved graphite layers. The nanoparticles were prepared by evaporating Co-Ni alloys and the shell of graphite layers was formed by in situ metal-catalytic growth on the surface of nanoparticles whose layer number was controlled by tuning the Co content of the alloys. By modulating the composition of the magnetic core and the layer number of the shell, the magnetic and dielectric properties of these core/shell structures are simultaneously optimized and their permeability and permittivity were improved to obtain the enhanced electromagnetic match. As a result, the bandwidth of reflection loss (RL) exceeding -20 dB (99% absorption) of the nanocapsules is 9.6 GHz for S1, 12.8 GHz for S2, 13.5 GHz for S3 and 14.2 GHz for S4. The optimal RL value reaches -53 dB at 13.2 GHz for an absorber thickness of 2.55 mm. An optimized

  2. Drug-induced gingival enlargement: biofilm control and surgical therapy with gallium-aluminum-arsenide (GaAlAs) diode laser-A 2-year follow-up.

    Science.gov (United States)

    de Oliveira Guaré, Renata; Costa, Soraya Carvalho; Baeder, Fernando; de Souza Merli, Luiz Antonio; Dos Santos, Maria Teresa Botti Rodrigues

    2010-01-01

    Drug-induced gingival enlargement has been reported in patients treated with various types of anticonvulsant drugs, and is generally associated with the presence of plaque, gingival inflammation, and a genetic predisposition. Effective treatment includes daily oral hygiene and periodic professional prophylaxis. However, in some patients, surgical removal of the gingival tissue overgrowth becomes necessary. The patient in this case report was mentally impaired and had severe drug-induced gingival enlargement. This report describes the initial protocol, the gingivectomy, and a 2-year follow-up. A diode laser was used as an effective and safe method to remove the patient's overgrown gingival tissue.

  3. Safranin O staining using a microwave oven.

    Science.gov (United States)

    Kahveci, Z; Minbay, F Z; Cavusoglu, L

    2000-11-01

    We investigated the effects of microwave irradiation on a safranin O staining method for paraffin sections of formalin fixed rabbit larynx. The control sections were stained according to the conventional method, and the experimental sections were stained in microwave oven for 10 sec at 360 W in Weigert's iron hematoxylin, and for 30 sec at 360 W in fast green and 0.1% safranin O staining solutions. Light microscopic examination of the sections revealed that the microwave heating did not adversely affect the staining properties of cartilage tissue compared to the conventional staining method. Small differences such as darker staining of the matrix and shrinkage of the cytoplasm was observed in some microwave treated sections. The present study revealed that microwave application can be used safely for the safranin O method with the advantage of reduced staining time.

  4. Microwave Breast Imaging Techniques

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Rubæk, Tonny

    2010-01-01

    This paper outlines the applicability of microwave radiation for breast cancer detection. Microwave imaging systems are categorized based on their hardware architecture. The advantages and disadvantages of various imaging techniques are discussed. The fundamental tradeoffs are indicated between v...

  5. Microwave Breast Imaging Techniques

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Rubæk, Tonny

    2010-01-01

    This paper outlines the applicability of microwave radiation for breast cancer detection. Microwave imaging systems are categorized based on their hardware architecture. The advantages and disadvantages of various imaging techniques are discussed. The fundamental tradeoffs are indicated between...

  6. Advances in microwaves 7

    CERN Document Server

    Young, Leo

    2013-01-01

    Advances in Microwaves, Volume 7 covers the developments in the study of microwaves. The book discusses the effect of surface roughness on the propagation of the TEM mode, as well as the voltage breakdown of microwave antennas. The text also describes the theory and design considerations of single slotted-waveguide linear arrays and the techniques and theories that led to the achievement of wide bandwidths and ultralow noise temperatures for communication applications. The book will prove invaluable to microwave engineers.

  7. Microwave Radiometer (MWR) Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Morris, VR

    2006-08-01

    The Microwave Radiometer (MWR) provides time-series measurements of column-integrated amounts of water vapor and liquid water. The instrument itself is essentially a sensitive microwave receiver. That is, it is tuned to measure the microwave emissions of the vapor and liquid water molecules in the atmosphere at specific frequencies.

  8. Nonlinearities in Microwave Superconductivity

    OpenAIRE

    Ledenyov, Dimitri O.; Ledenyov, Viktor O.

    2012-01-01

    The research is focused on the modeling of nonlinear properties of High Temperature Superconducting (HTS) thin films, using Bardeen, Cooper, Schrieffer and Lumped Element Circuit theories, with purpose to enhance microwave power handling capabilities of microwave filters and optimize design of microwave circuits in micro- and nano- electronics.

  9. Design of multiple-layer microwave absorbing structure based on rice husk and carbon nanotubes

    Science.gov (United States)

    Seng, Lee Yeng; Wee, F. H.; Rahim, H. A.; AbdulMalek, MohamedFareq; You, Y. K.; Liyana, Z.; Ezanuddin, A. A. M.

    2017-01-01

    This paper presents a multiple-layered microwave absorber using rice husk and carbon nanotube composite. The dielectric properties of each layer composite were measured and analysed. The different layer of microwave absorber enables to control the microwave absorption performance. The microwave absorption performances are demonstrated through measurements of reflectivity over the frequency range 2-18 GHz. An improvement of microwave absorption application as wideband electromagnetic wave absorbers.

  10. Hyperchaos via X-Diode

    DEFF Research Database (Denmark)

    Lindberg, Erik; Tamasevicius, A.; Cenys, A.

    1998-01-01

    A Chaos diode (X-diode) with a hysteric current-voltage characteristic has been used to generate hyperchaotic oscillations characterized with multiple positive Lyapunov exponents. The hyperchaotic oscillators comprise a X-diode in parallel with an M'th order LC loop (M.GE.4). Numerical simulations...... and hardware experiments have beeen performed. An appropriate mathematical model is provided and is used to calculate the Lyapunov exponents. Synchronization properties have been investigated....

  11. Diode, transistor & fet circuits manual

    CERN Document Server

    Marston, R M

    2013-01-01

    Diode, Transistor and FET Circuits Manual is a handbook of circuits based on discrete semiconductor components such as diodes, transistors, and FETS. The book also includes diagrams and practical circuits. The book describes basic and special diode characteristics, heat wave-rectifier circuits, transformers, filter capacitors, and rectifier ratings. The text also presents practical applications of associated devices, for example, zeners, varicaps, photodiodes, or LEDs, as well as it describes bipolar transistor characteristics. The transistor can be used in three basic amplifier configuration

  12. A practical guide to handling laser diode beams

    CERN Document Server

    Sun, Haiyin

    2015-01-01

    This book offers the reader a practical guide to the control and characterization of laser diode beams.  Laser diodes are the most widely used lasers, accounting for 50% of the global laser market.  Correct handling of laser diode beams is the key to the successful use of laser diodes, and this requires an in-depth understanding of their unique properties. Following a short introduction to the working principles of laser diodes, the book describes the basics of laser diode beams and beam propagation, including Zemax modeling of a Gaussian beam propagating through a lens.  The core of the book is concerned with laser diode beam manipulations: collimating and focusing, circularization and astigmatism correction, coupling into a single mode optical fiber, diffractive optics and beam shaping, and manipulation of multi transverse mode beams.  The final chapter of the book covers beam characterization methods, describing the measurement of spatial and spectral properties, including wavelength and linewidth meas...

  13. Remote Control System of the TJ-II Microwave Transmission Lines Mirrors; Sistema de Control Remoto de los Espejos de las Lineas de Transmision de Microondas del TJ-II

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Sanchez, A.; Fernandez, A.; Cappa, A.; Gama, J. de la; Olivares, J.; Garcia, R.; Chamorro, M.

    2007-09-27

    The ECRH system of the TJ-II stellarator has two gyrotrons, which deliver a maximum power of 300 kW each at a frequency of 53.2 GHz. Another 28 GHz gyrotron will be used to heat the plasma by electron Bernstein waves (EBWH). The microwave power is transmitted from the gyrotrons to the vacuum chamber by two quasi-optical transmission lines for ECRH and a corrugated waveguide for EBWH. All transmission lines have an internal movable mirror inside the vacuum chamber to focus the beam and to be able to change the launching angle. The control of the beam polarization is very important and the lines have two corrugated mirrors, which actuate as polarizers. In this report the control system of the position of these three internal mirrors and the polarizers of the EBWH transmission line is described. (Author) 20 refs.

  14. Active graphene–silicon hybrid diode for terahertz waves

    OpenAIRE

    Li, Quan; Tian, Zhen; Zhang, Xueqian; Singh, Ranjan; Du, Liangliang; Gu, Jianqiang; Han, Jiaguang; Zhang, Weili

    2015-01-01

    Controlling the propagation properties of the terahertz waves in graphene holds great promise in enabling novel technologies for the convergence of electronics and photonics. A diode is a fundamental electronic device that allows the passage of current in just one direction based on the polarity of the applied voltage. With simultaneous optical and electrical excitations, we experimentally demonstrate an active diode for the terahertz waves consisting of a graphene–silicon hybrid film. The di...

  15. Proton-conducting beta"-alumina via microwave-assisted synthesis and mechanism of enhanced corrosion prevention of a zinc rich coating with electronic control

    Science.gov (United States)

    Kirby, Brent William

    Proton Conducting beta-alumina via Microwave Assisted Synthesis. The microwave assisted synthesis of proton conducting Mg- and Li-stabilized NH4+/H3O+ beta-alumina from a solution based gel precursor is reported. beta-alumina is a ceramic fast ion conductor containing two-dimensional sheets of mobile cations. Na +-beta-alumina is the most stable at the sintering temperatures (1740°C) reached in a modified microwave oven, and can be ion exchanged to the K+ form and then to the NH4+/H 3O+ form. beta-phase impurity is found to be 20% for Mg-stabilized material and 30-40% for Li-stabilized material. The composition of the proton conducting form produced here is deficient in NH4 + as compared to the target composition (NH4)1.00 (H3O)0.67Mg0.67Al10.33O 17. Average grain conductivity for Li-stabilized material at 150°C is 6.6x10-3 +/- 1.6x10-3 S/cm with 0.29 +/- 0.05 eV activation energy, in agreement with single crystal studies in the literature. Grain boundary conductivity is found to be higher in the Li-stabilized material. A hydrogen bond energy hypothesis is presented to explain these differences. Li-stabilized NH4+/H3O + beta-alumina is demonstrated as a fuel cell electrolyte, producing 28 muA/cm2 of electrical current at 0.5 V. Mechanism of Enhanced Corrosion Prevention of a Zinc Rich Coating with Electronic Control. A corrosion inhibition system consisting of high weight-loading zinc rich coating applied to steel panels is examined. An electronic control unit (ECU) consisting of a battery and a large capacitor in series with the panel is shown to improve corrosion protection upon immersion in 3% NaCl solution. Weekly solution changes to avoid zinc saturation in solution system were necessary to see well differentiated results. The corrosion product, hydrozincite [Zn5(CO3) 2(OH)6] is observed to deposit within the pores of the coating and on the surface as a barrier layer. Simonkolleite [Zn5(OH) 8Cl2·H2O] is found to form in place of the original zinc particles

  16. High brightness microwave lamp

    Science.gov (United States)

    Kirkpatrick, Douglas A.; Dolan, James T.; MacLennan, Donald A.; Turner, Brian P.; Simpson, James E.

    2003-09-09

    An electrodeless microwave discharge lamp includes a source of microwave energy, a microwave cavity, a structure configured to transmit the microwave energy from the source to the microwave cavity, a bulb disposed within the microwave cavity, the bulb including a discharge forming fill which emits light when excited by the microwave energy, and a reflector disposed within the microwave cavity, wherein the reflector defines a reflective cavity which encompasses the bulb within its volume and has an inside surface area which is sufficiently less than an inside surface area of the microwave cavity. A portion of the reflector may define a light emitting aperture which extends from a position closely spaced to the bulb to a light transmissive end of the microwave cavity. Preferably, at least a portion of the reflector is spaced from a wall of the microwave cavity. The lamp may be substantially sealed from environmental contamination. The cavity may include a dielectric material is a sufficient amount to require a reduction in the size of the cavity to support the desired resonant mode.

  17. The effect of phase stabilization of microwave oscillations in nanosecond Gunn oscillators

    Science.gov (United States)

    Konev, V. Yu.; Klimov, A. I.; Koval'chuk, O. B.; Gubanov, V. P.; Kozhevnikov, V. Yu.; Kozyrev, A. V.; Torkhov, N. A.

    2013-11-01

    The effect of the semiconductor structure of an oscillator diode on the phase stabilization of microwave oscillations in a nanosecond Gunn oscillator by using a modulating voltage pulse edge is investigated. Numerical simulation is employed to determine phase deviations depending on the scatter of pulseedge duration and pulse amplitude. The standard deviation of phase-delay time of microwave oscillations in the oscillator with regard to a constant level at the modulating pulse edge and the standard deviation of phase difference of microwave oscillations in two electrodynamically insulated oscillators connected in parallel to one and the same modulator have been measured.

  18. STIR: Microwave Response of Carbon Nanotubes in Polymer Nanocomposite Welds

    Science.gov (United States)

    2016-01-28

    100 W) microwave radiation at 2.45 GHz in a controlled environment. We used a forward-looking infrared (FLIR) camera to image the temperature...sample can be monitored during microwave exposure by using the FLIR camera . The power was controlled by hand to ensure a consistent thermal history...the thermal conductivity of the nanocomposite would also change with temperature. 2. Can simulations of the coupled microwave field, dielectric

  19. Fabrication and characteristics of GaAs-AlGaAs tunable laser diodes with DBR and phase-control sections integrated by compositional disordering of a quantum well

    Science.gov (United States)

    Hirata, Takaaki; Maeda, Minoru; Suehiro, Masayuki; Hosomatsu, Haruo

    1991-06-01

    GaAs-AlGaAs rib-waveguide graded-index separate-confinement heterostructure (GRINSCH) single-quantum-well (SQW) tunable distributed Bragg reflector (DBR) laser diodes were fabricated by (EB) lithography, ion implantation, and two-step metalorganic vapor phase epitaxy (MOVPE) growth. Active and passive waveguides were monolithically integrated by the compositional disordering of quantum-well heterostructures using silicon ion implantation. First-order gratings and rib waveguides were adopted with EB lithography to improve lasing characteristics, and they have wide application to photonic integrated circuits (PICs). Waveguide losses of partially disordered GRINSCH-SQW passive waveguides were as low as 4.4/cm at the lasing wavelength. A narrow linewidth as low as 560 kHz and a frequency tuning of more than 2.9 THz were obtained. The results show that this fabrication process is useful for PICs.

  20. Current transport mechanisms in mercury cadmium telluride diode

    Energy Technology Data Exchange (ETDEWEB)

    Gopal, Vishnu, E-mail: vishnu-46@yahoo.com, E-mail: wdhu@mail.sitp.ac.cn [Institute of Defence Scientists and Technologists, CFEES Complex, Brig. S. K. Majumdar Marg, Delhi 110054 (India); Li, Qing; He, Jiale; Hu, Weida, E-mail: vishnu-46@yahoo.com, E-mail: wdhu@mail.sitp.ac.cn [National Lab for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); He, Kai; Lin, Chun [Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China)

    2016-08-28

    This paper reports the results of modelling of the current-voltage characteristics (I-V) of a planar mid-wave Mercury Cadmium Telluride photodiode in a gate controlled diode experiment. It is reported that the diode exhibits nearly ideal I-V characteristics under the optimum surface potential leading to the minimal surface leakage current. Deviations from the optimum surface potential lead to non ideal I–V characteristics, indicating a strong relationship between the ideality factor of the diode with its surface leakage current. Diode's I–V characteristics have been modelled over a range of gate voltages from −9 V to −2 V. This range of gate voltages includes accumulation, flat band, and depletion and inversion conditions below the gate structure of the diode. It is shown that the I–V characteristics of the diode can be very well described by (i) thermal diffusion current, (ii) ohmic shunt current, (iii) photo-current due to background illumination, and (iv) excess current that grows by the process of avalanche multiplication in the gate voltage range from −3 V to −5 V that corresponds to the optimum surface potential. Outside the optimum gate voltage range, the origin of the excess current of the diode is associated with its high surface leakage currents. It is reported that the ohmic shunt current model applies to small surface leakage currents. The higher surface leakage currents exhibit a nonlinear shunt behaviour. It is also shown that the observed zero-bias dynamic resistance of the diode over the entire gate voltage range is the sum of ohmic shunt resistance and estimated zero-bias dynamic resistance of the diode from its thermal saturation current.

  1. Current transport mechanisms in mercury cadmium telluride diode

    Science.gov (United States)

    Gopal, Vishnu; Li, Qing; He, Jiale; He, Kai; Lin, Chun; Hu, Weida

    2016-08-01

    This paper reports the results of modelling of the current-voltage characteristics (I-V) of a planar mid-wave Mercury Cadmium Telluride photodiode in a gate controlled diode experiment. It is reported that the diode exhibits nearly ideal I-V characteristics under the optimum surface potential leading to the minimal surface leakage current. Deviations from the optimum surface potential lead to non ideal I-V characteristics, indicating a strong relationship between the ideality factor of the diode with its surface leakage current. Diode's I-V characteristics have been modelled over a range of gate voltages from -9 V to -2 V. This range of gate voltages includes accumulation, flat band, and depletion and inversion conditions below the gate structure of the diode. It is shown that the I-V characteristics of the diode can be very well described by (i) thermal diffusion current, (ii) ohmic shunt current, (iii) photo-current due to background illumination, and (iv) excess current that grows by the process of avalanche multiplication in the gate voltage range from -3 V to -5 V that corresponds to the optimum surface potential. Outside the optimum gate voltage range, the origin of the excess current of the diode is associated with its high surface leakage currents. It is reported that the ohmic shunt current model applies to small surface leakage currents. The higher surface leakage currents exhibit a nonlinear shunt behaviour. It is also shown that the observed zero-bias dynamic resistance of the diode over the entire gate voltage range is the sum of ohmic shunt resistance and estimated zero-bias dynamic resistance of the diode from its thermal saturation current.

  2. Reconfigurable nonreciprocity with nonlinear Fano diode

    OpenAIRE

    Xu, Yi; Miroshnichenko, Andrey E.

    2013-01-01

    We propose a dynamically tunable nonreciprocal response for wave propagations by employing nonlinear Fano resonances. We demonstrate that transmission contrast of waves propagation in opposite directions can be controlled by excitation signal. In particular, the unidirectional transmission can be flipped at different times of a pulse, resembling a diode operation with {\\em dynamical reconfigurable nonreciprocity}. The key mechanism is the interaction between the linear and nonlinear Fano reso...

  3. Microwave endometrial ablation as an alternative to hysterectomy for the emergent control of uterine bleeding in patients who are poor surgical candidates

    OpenAIRE

    2008-01-01

    Background Microwave endometrial ablation is a new, minimally invasive treatment option for menorrhagia. Its popularity in many countries is increasing due to its safety and simplicity. Cases We treated menorrhagia due to submucosal myomas in two patients with a modified microwave endometrial ablation device. Surgery was contraindicated in the first patient secondary to medical co-morbidities and in the second patient because of acute hemorrhagic shock. In both cases, the operation was highly...

  4. On the intrinsic moisture permeation rate of remote microwave plasma-deposited silicon nitride layers

    NARCIS (Netherlands)

    Assche, F.J.H. Van; Unnikrishnan, S.; Michels, J.J.; Mol, A.M.B. van; Weijer, P. van de; Sanden, M.C.M. van de; Creatore, M.

    2014-01-01

    We report on a low substrate temperature (110°C) remote microwave plasma-enhanced chemical vapor deposition (PECVD) process of silicon nitride barrier layers against moisture permeation for organic light emitting diodes (OLEDs) and other moisture sensitive devices such as organic photovoltaic cells

  5. Microwave Power Transmission Using Electromagnetic Coupling of Open-Ring Resonators

    Science.gov (United States)

    2012-11-01

    Ao, I. Awai and Y. Ohno, “Wireless Inter-Chip Signal Transmission by Electromagnetic Coupling of Open-Ring Resonators,” Japanese Journal of Applied Physics , vol...Y Hu, H. Kawai, N. Shinohara, N. Niwa, and Y. Ohno, : GaN Schottky Diodes for Microwave Power Rectification, Japanese Journal of Applied Physics , Vol

  6. Progress in the development of active heat sink for high-power laser diodes

    Science.gov (United States)

    Vetrovec, John; Feeler, Ryan; Bonham, Steve

    2010-02-01

    We report on the development of a novel active heat sink for high-power laser diodes offering unparalleled capacity in high-heat flux handling and temperature control. The heat sink receives diode waste heat at high flux and transfers it at reduced flux to environment, coolant fluid, heat pipe, or structure. Thermal conductance of the heat sink is electronically adjustable, allowing for precise control of diode temperature and the output light wavelength. When pumping solid-state lasers, diode wavelength can be precisely tuned to the absorption features of the laser gain medium. This paper presents the AHS concept, scaling laws, model predictions, and data from initial testing.

  7. Modeling of SVM Diode Clamping Three-Level Inverter Connected to Grid

    DEFF Research Database (Denmark)

    Guo, Yougui; Zeng, Ping; Zhu, Jieqiong

    2011-01-01

    PLECS is used to model the diode clamping three-level inverter connected to grid and good results are obtained. First the output voltage SVM is described for diode clamping three-level inverter with loads connected to Y. Then the output voltage SVM of diode clamping three-level inverter is simply...... is very powerful tool to real power circuits and it is very easy to simulate them. They have also verified that SVM control strategy is feasible to control the diode clamping three-level inverter....

  8. Diode laser applications in urology

    Science.gov (United States)

    Sam, Richard C.; Esch, Victor C.

    1995-05-01

    Diode lasers are air-cooled, efficient, compact devices which have the potential of very low cost when produced in quantity. The characteristics of diode lasers are discussed. Their applications in interstitial thermal treatment of the prostate, and laser ablation of prostate tissues, will be presented.

  9. Active graphene-silicon hybrid diode for terahertz waves.

    Science.gov (United States)

    Li, Quan; Tian, Zhen; Zhang, Xueqian; Singh, Ranjan; Du, Liangliang; Gu, Jianqiang; Han, Jiaguang; Zhang, Weili

    2015-05-11

    Controlling the propagation properties of the terahertz waves in graphene holds great promise in enabling novel technologies for the convergence of electronics and photonics. A diode is a fundamental electronic device that allows the passage of current in just one direction based on the polarity of the applied voltage. With simultaneous optical and electrical excitations, we experimentally demonstrate an active diode for the terahertz waves consisting of a graphene-silicon hybrid film. The diode transmits terahertz waves when biased with a positive voltage while attenuates the wave under a low negative voltage, which can be seen as an analogue of an electronic semiconductor diode. Here, we obtain a large transmission modulation of 83% in the graphene-silicon hybrid film, which exhibits tremendous potential for applications in designing broadband terahertz modulators and switchable terahertz plasmonic and metamaterial devices.

  10. Active graphene–silicon hybrid diode for terahertz waves

    Science.gov (United States)

    Li, Quan; Tian, Zhen; Zhang, Xueqian; Singh, Ranjan; Du, Liangliang; Gu, Jianqiang; Han, Jiaguang; Zhang, Weili

    2015-01-01

    Controlling the propagation properties of the terahertz waves in graphene holds great promise in enabling novel technologies for the convergence of electronics and photonics. A diode is a fundamental electronic device that allows the passage of current in just one direction based on the polarity of the applied voltage. With simultaneous optical and electrical excitations, we experimentally demonstrate an active diode for the terahertz waves consisting of a graphene–silicon hybrid film. The diode transmits terahertz waves when biased with a positive voltage while attenuates the wave under a low negative voltage, which can be seen as an analogue of an electronic semiconductor diode. Here, we obtain a large transmission modulation of 83% in the graphene–silicon hybrid film, which exhibits tremendous potential for applications in designing broadband terahertz modulators and switchable terahertz plasmonic and metamaterial devices. PMID:25959596

  11. Active graphene-silicon hybrid diode for terahertz waves

    Science.gov (United States)

    Li, Quan; Tian, Zhen; Zhang, Xueqian; Singh, Ranjan; Du, Liangliang; Gu, Jianqiang; Han, Jiaguang; Zhang, Weili

    2015-05-01

    Controlling the propagation properties of the terahertz waves in graphene holds great promise in enabling novel technologies for the convergence of electronics and photonics. A diode is a fundamental electronic device that allows the passage of current in just one direction based on the polarity of the applied voltage. With simultaneous optical and electrical excitations, we experimentally demonstrate an active diode for the terahertz waves consisting of a graphene-silicon hybrid film. The diode transmits terahertz waves when biased with a positive voltage while attenuates the wave under a low negative voltage, which can be seen as an analogue of an electronic semiconductor diode. Here, we obtain a large transmission modulation of 83% in the graphene-silicon hybrid film, which exhibits tremendous potential for applications in designing broadband terahertz modulators and switchable terahertz plasmonic and metamaterial devices.

  12. Microwave Treatment for Cardiac Arrhythmias

    Science.gov (United States)

    Hernandez-Moya, Sonia

    2009-01-01

    NASA seeks to transfer the NASA developed microwave ablation technology, designed for the treatment of ventricular tachycardia (irregular heart beat), to industry. After a heart attack, many cells surrounding the resulting scar continue to live but are abnormal electrically; they may conduct impulses unusually slowly or fire when they would typically be silent. These diseased areas might disturb smooth signaling by forming a reentrant circuit in the muscle. The objective of microwave ablation is to heat and kill these diseased cells to restore appropriate electrical activity in the heart. This technology is a method and apparatus that provides for propagating microwave energy into heart tissues to produce a desired temperature profile therein at tissue depths sufficient for thermally ablating arrhythmogenic cardiac tissue while preventing excessive heating of surrounding tissues, organs, and blood. A wide bandwidth double-disk antenna is effective for this purpose over a bandwidth of about six gigahertz. A computer simulation provides initial screening capabilities for an antenna such as antenna, frequency, power level, and power application duration. The simulation also allows optimization of techniques for specific patients or conditions. In comparison with other methods that involve direct-current pulses or radio frequencies below 1 GHz, this method may prove more effective in treating ventricular tachycardia. This is because the present method provides for greater control of the location, cross-sectional area, and depth of a lesion via selection of the location and design of the antenna and the choice of microwave power and frequency.

  13. Adjustable Fiber Optic Microwave Transversal Filters

    Science.gov (United States)

    Shadaram, Mehdi; Lutes, George F.; Logan, Ronald T.; Maleki, Lutfollah

    1994-01-01

    Microwave transversal filters implemented as adjustable tapped fiber optic delay lines developed. Main advantages of these filters (in comparison with conventional microwave transversal filters) are small size, light weight, no need for matching of radio-frequency impedances, no need for shielding against electromagnetic radiation at suboptical frequencies, no need for mechanical tuning, high stability of amplitude and phase, and active control of transfer functions. Weights of taps in fiber optic delay lines adjusted.

  14. Template nanowires for spintronics applications: nanomagnet microwave resonators functioning in zero applied magnetic field.

    Science.gov (United States)

    Mourachkine, A; Yazyev, O V; Ducati, C; Ansermet, J-Ph

    2008-11-01

    Low-cost spintronic devices functioning in zero applied magnetic field are required for bringing the idea of spin-based electronics into the real-world industrial applications. Here we present first microwave measurements performed on nanomagnet devices fabricated by electrodeposition inside porous membranes. In the paper, we discuss in details a microwave resonator consisting of three nanomagnets, which functions in zero external magnetic field. By applying a microwave signal at a particular frequency, the magnetization of the middle nanomagnet experiences the ferromagnetic resonance (FMR), and the device outputs a measurable direct current (spin-torque diode effect). Alternatively, the nanodevice can be used as a microwave oscillator functioning in zero field. To test the resonators at microwave frequencies, we developed a simple measurement setup.

  15. Coherent and noncoherent low-power diodes in clinical practice

    Science.gov (United States)

    Antipa, Ciprian; Pascu, Mihail-Lucian; Stanciulescu, Viorica; Vlaiculescu, Mihaela; Ionescu, Elena; Bordea, Daniel

    1997-05-01

    Clinical efficacy of the low power laser (LPL) in medical treatments is still not well established. In a double blind, placebo controlled study, we tried to find out first which type of LPL is more efficient, and second if coherence is an important character for clinical efficacy. We treated 1228 patients having different rheumatic diseases, with low power diode, used as follows: A group: IR coherent diode, continuous emission, 3 mW power; B group: IR coherent diode, pulsed emission, output power about 3 mW; C group: IR noncoherent diode continuous emission 9 mW power; D group: both IR diode lasers (continuous or pulsed) and HeNe laser, continuous emission, 2 mW power; E group: placebo laser as control group. The energy dose used for every group was the same, as well as the clinical protocols. The positive results were: 66.16% for A group; 64.06% for B group; 48.87% for C group; 76.66% for D group, and 39.07% for E group. Finally, we showed that LPL is really efficient in the treatment of some rheumatic diseases, especially when red and IR diode laser were used in combination. The type of emission (continuous or pulsed) is not important, but coherence is obviously necessary for clinical efficacy.

  16. Gallium phosphide high temperature diodes

    Science.gov (United States)

    Chaffin, R. J.; Dawson, L. R.

    1981-01-01

    High temperature (300 C) diodes for geothermal and other energy applications were developed. A comparison of reverse leakage currents of Si, GaAs, and GaP was made. Diodes made from GaP should be usable to 500 C. A Liquid Phase Epitaxy (LPE) process for producing high quality, grown junction GaP diodes is described. This process uses low vapor pressure Mg as a dopant which allows multiple boat growth in the same LPE run. These LPE wafers were cut into die and metallized to make the diodes. These diodes produce leakage currents below ten to the -9th power A/sq cm at 400 C while exhibiting good high temperature rectification characteristics. High temperature life test data is presented which shows exceptional stability of the V-I characteristics.

  17. Using your microwave oven. Lesson 6, Microwave oven management

    OpenAIRE

    Woodard, Janice Emelie, 1929-

    1984-01-01

    Discusses cooking and reheating foods in microwave ovens, and adapting conventional recipes for the microwave. Revised Includes the publication: Adapting conventional recipes to microwave cooking : fact sheet 84 by Janice Woodard, Rebecca Lovingood, R.H. Trice.

  18. Using your microwave oven. Lesson 6, Microwave oven management

    OpenAIRE

    Woodard, Janice Emelie, 1929-

    1984-01-01

    Discusses cooking and reheating foods in microwave ovens, and adapting conventional recipes for the microwave. Revised Includes the publication: Adapting conventional recipes to microwave cooking : fact sheet 84 by Janice Woodard, Rebecca Lovingood, R.H. Trice.

  19. Microwave phase shifter with controllable power response based on slow-and fast-light effects in semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Xue, Weiqi; Sales, Salvador; Capmany, Jose

    2009-01-01

    We suggest and experimentally demonstrate a method for increasing the tunable rf phase shift of semiconductor waveguides while at the same time enabling control of the rf power. This method is based on the use of slow- and fast-light effects in a cascade of semiconductor optical amplifiers combined...

  20. Cryogenic coaxial microwave filters

    CERN Document Server

    Tancredi, G; Meeson, P J

    2014-01-01

    At millikelvin temperatures the careful filtering of electromagnetic radiation, especially in the microwave regime, is critical for controlling the electromagnetic environment for experiments in fields such as solid-state quantum information processing and quantum metrology. We present a design for a filter consisting of small diameter dissipative coaxial cables that is straightforward to construct and provides a quantitatively predictable attenuation spectrum. We describe the fabrication process and demonstrate that the performance of the filters is in good agreement with theoretical modelling. We further perform an indicative test of the performance of the filters by making current-voltage measurements of small, underdamped Josephson Junctions at 15 mK and we present the results.

  1. Superconducting quantum node for entanglement and storage of microwave radiation.

    Science.gov (United States)

    Flurin, E; Roch, N; Pillet, J D; Mallet, F; Huard, B

    2015-03-06

    Superconducting circuits and microwave signals are good candidates to realize quantum networks, which are the backbone of quantum computers. We have realized a quantum node based on a 3D microwave superconducting cavity parametrically coupled to a transmission line by a Josephson ring modulator. We first demonstrate the time-controlled capture, storage, and retrieval of an optimally shaped propagating microwave field, with an efficiency as high as 80%. We then demonstrate a second essential ability, which is the time-controlled generation of an entangled state distributed between the node and a microwave channel.

  2. Superconducting Quantum Node for Entanglement and Storage of Microwave Radiation

    Science.gov (United States)

    Flurin, E.; Roch, N.; Pillet, J. D.; Mallet, F.; Huard, B.

    2015-03-01

    Superconducting circuits and microwave signals are good candidates to realize quantum networks, which are the backbone of quantum computers. We have realized a quantum node based on a 3D microwave superconducting cavity parametrically coupled to a transmission line by a Josephson ring modulator. We first demonstrate the time-controlled capture, storage, and retrieval of an optimally shaped propagating microwave field, with an efficiency as high as 80%. We then demonstrate a second essential ability, which is the time-controlled generation of an entangled state distributed between the node and a microwave channel.

  3. Integrated software package for laser diodes characterization

    Science.gov (United States)

    Sporea, Dan G.; Sporea, Radu A.

    2003-10-01

    The characteristics of laser diodes (wavelength of the emitted radiation, output optical power, embedded photodiode photocurrent, threshold current, serial resistance, external quantum efficiency) are strongly influenced by their driving circumstances (forward current, case temperature). In order to handle such a complex investigation in an efficient and objective manner, the operation of several instruments (a laser diode driver, a temperature controller, a wavelength meter, a power meter, and a laser beam analyzer) is synchronously controlled by a PC, through serial and GPIB communication. For each equipment, instruments drivers were designed using the industry standards graphical programming environment - LabVIEW from National Instruments. All the developed virtual instruments operate under the supervision of a managing virtual instrument, which sets the driving parameters for each unit under test. The manager virtual instrument scans as appropriate the driving current and case temperature values for the selected laser diode. The software enables data saving in Excel compatible files. In this way, sets of curves can be produced according to the testing cycle needs.

  4. A New High Power Microwave Source Operated at Low Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    YANG Jian-Hua; ZHANG Ya-Zhou; ZHANG Jian-De; SHU-Ting; LI Chuan-Lu

    2003-01-01

    A new type of high power microwave source operated at Jow magnetic Geld is proposed and studied by the particle-in-cell (PIC) method. An oversized uniform backward-wave-oscillator-like structure is connected to a tapered slow-wave structure by a resonant cavity. In this device, the electron beam current is effectively used to yield microwaves with high efficiency, and the mode is locked in a wide range of diode voltage to reduce the requirement to the voltage wave form. The PIC simulation results show that a peat microwave power of 2.1 GW (averaged 1.1 GW) with a pure TMoi mode at 10. 7 GHz is radiated with 4.1 GW input beam power, the frequency remains approximately the same when the diode voltage changed from 300 kV to 700 kV.

  5. Microwave and RF engineering

    CERN Document Server

    Sorrentino, Roberto

    2010-01-01

    An essential text for both students and professionals, combining detailed theory with clear practical guidance This outstanding book explores a large spectrum of topics within microwave and radio frequency (RF) engineering, encompassing electromagnetic theory, microwave circuits and components. It provides thorough descriptions of the most common microwave test instruments and advises on semiconductor device modelling. With examples taken from the authors' own experience, this book also covers:network and signal theory;electronic technology with guided electromagnetic pr

  6. Simultaneous quantitative determination of six active components in traditional Chinese medicinal preparation Cerebralcare Granule® by RP-HPLC coupled with diode array detection for quality control.

    Science.gov (United States)

    Wang, Xiang-yang; Ma, Xiao-hui; Li, Wei; Chu, Yang; Guo, Jia-hua; Zhou, Shui-ping; Zhu, Yong-hong

    2014-09-01

    A simple, accurate and reliable method for the simultaneous separation and determination of six active components (protocatechuic acid, chlorogenic acid, caffeic acid, paeoniflorin, ferulic acid and rosmarinic acid) in traditional Chinese medicinal preparation Cerebralcare Granule(®) (CG) was developed using reverse-phase high-performance liquid chromatography coupled with diode array detector detection. The chromatographic separation was performed on a Hypersil GOLD C18 column with aqueous formic acid (0.1%, v/v) and acetonitrile as mobile phase at a flow rate of 0.2 ml/min at 30 °C. Because of the different UV characteristics of these components, change detection wavelength method was used for quantitative analysis. All of the analytes showed good linearity (r > 0.9992). The established method showed good precision and relative standard deviations (%) for intra-day and inter-day variations of 0.15-1.81 and 0.11-1.98%, respectively. The validated method was successfully applied to the simultaneously determination of six active components in CG from different batches.

  7. High Frequency Performance of GaN Based IMPATT Diodes

    Directory of Open Access Journals (Sweden)

    B. Chakrabarti

    2011-08-01

    Full Text Available IMPATT is a p+n junction diode reversed bias to breakdown and can generate microwave power when properly embedded in a resonant cavity. Till emergence on 1965 day by day it became more powerful solid state source for microwave as well as mm-wave frequency range. To get higher efficiency and power output different structures like SDR, DDR, DAR, lo-high-lo, etc. were proposed and developed by different scientists over the years. Then the IMPATT development started with different semiconductor materials like GaAs, InP, GaN, etc. along with Silicon to achieve higher efficiency, power output and frequency range. In this paper the performance of GaN based SDR IMPATT have thoroughly studied in terms of (i electric field profile[E(x] (iinormalized current density profile [P(x] (iii Susceptance Vs Conductance characteristics (ivRF power output (v negative resistivity profile [R(x] of the diodes through simulation scheme. It is being observed that the efficiency is 17.9% at Ka-band and because of the very high breakdown voltage, power output is as high as1.56W in comparison with other frequency band of operations.

  8. Advanced microwave processing concepts

    Energy Technology Data Exchange (ETDEWEB)

    Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    The purpose of this work is to explore the feasibility of several advanced microwave processing concepts to develop new energy-efficient materials and processes. The project includes two tasks: (1) commercialization of the variable-frequency microwave furnace; and (2) microwave curing of polymeric materials. The variable frequency microwave furnace, whose initial conception and design was funded by the AIM Materials Program, allows the authors, for the first time, to conduct microwave processing studies over a wide frequency range. This novel design uses a high-power traveling wave tube (TWT) originally developed for electronic warfare. By using this microwave source, one can not only select individual microwave frequencies for particular experiments, but also achieve uniform power densities over a large area by the superposition of many different frequencies. Microwave curing of various thermoset resins will be studied because it holds the potential of in-situ curing of continuous-fiber composites for strong, lightweight components or in-situ curing of adhesives, including metal-to-metal. Microwave heating can shorten curing times, provided issues of scaleup, uniformity, and thermal management can be adequately addressed.

  9. Advanced microwave processing concepts

    Energy Technology Data Exchange (ETDEWEB)

    Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L. [Oak Ridge National Laboratory, TN (United States)

    1995-05-01

    The purpose of this work is to explore the feasibility of several advanced microwave processing concepts to develop new energy-efficient materials and processes. The project includes two tasks: (1) commercialization of the variable-frequency microwave furnace; and (2) microwave curing of polymer composites. The variable frequency microwave furnace, whose initial conception and design was funded by the AIC Materials Program, will allow us, for the first time, to conduct microwave processing studies over a wide frequency range. This novel design uses a high-power traveling wave tube (TWT) originally developed for electronic warfare. By using this microwave source, one can not only select individual microwave frequencies for particular experiments, but also achieve uniform power densities over a large area by the superposition of many different frequencies. Microwave curing of thermoset resins will be studied because it hold the potential of in-situ curing of continuous-fiber composites for strong, lightweight components. Microwave heating can shorten curing times, provided issues of scaleup, uniformity, and thermal management can be adequately addressed.

  10. Advances in microwaves 3

    CERN Document Server

    Young, Leo

    2013-01-01

    Advances in Microwaves, Volume 3 covers the advances and applications of microwave signal transmission and Gunn devices. This volume contains six chapters and begins with descriptions of ground-station antennas for space communications. The succeeding chapters deal with beam waveguides, which offer interesting possibilities for transmitting microwave energy, as well as with parallel or tubular beams from antenna apertures. A chapter discusses the electron transfer mechanism and the velocity-field characteristics, with a particular emphasis on the microwave properties of Gunn oscillators. The l

  11. Modulated microwave microscopy and probes used therewith

    Science.gov (United States)

    Lai, Keji; Kelly, Michael; Shen, Zhi-Xun

    2012-09-11

    A microwave microscope including a probe tip electrode vertically positionable over a sample and projecting downwardly from the end of a cantilever. A transmission line connecting the tip electrode to the electronic control system extends along the cantilever and is separated from a ground plane at the bottom of the cantilever by a dielectric layer. The probe tip may be vertically tapped near or at the sample surface at a low frequency and the microwave signal reflected from the tip/sample interaction is demodulated at the low frequency. Alternatively, a low-frequency electrical signal is also a non-linear electrical element associated with the probe tip to non-linearly interact with the applied microwave signal and the reflected non-linear microwave signal is detected at the low frequency. The non-linear element may be semiconductor junction formed near the apex of the probe tip or be an FET formed at the base of a semiconducting tip.

  12. A monolithic integrated photonic microwave filter

    Science.gov (United States)

    Fandiño, Javier S.; Muñoz, Pascual; Doménech, David; Capmany, José

    2016-12-01

    Meeting the increasing demand for capacity in wireless networks requires the harnessing of higher regions in the radiofrequency spectrum, reducing cell size, as well as more compact, agile and power-efficient base stations that are capable of smoothly interfacing the radio and fibre segments. Fully functional microwave photonic chips are promising candidates in attempts to meet these goals. In recent years, many integrated microwave photonic chips have been reported in different technologies. To the best of our knowledge, none has monolithically integrated all the main active and passive optoelectronic components. Here, we report the first demonstration of a tunable microwave photonics filter that is monolithically integrated into an indium phosphide chip. The reconfigurable radiofrequency photonic filter includes all the necessary elements (for example, lasers, modulators and photodetectors), and its response can be tuned by means of control electric currents. This is an important step in demonstrating the feasibility of integrated and programmable microwave photonic processors.

  13. RF and microwave microelectronics packaging II

    CERN Document Server

    Sturdivant, Rick

    2017-01-01

    Reviews RF, microwave, and microelectronics assembly process, quality control, and failure analysis Bridges the gap between low cost commercial and hi-res RF/Microwave packaging technologies Engages in an in-depth discussion of challenges in packaging and assembly of advanced high-power amplifiers This book presents the latest developments in packaging for high-frequency electronics. It is a companion volume to “RF and Microwave Microelectronics Packaging” (2010) and covers the latest developments in thermal management, electrical/RF/thermal-mechanical designs and simulations, packaging and processing methods, and other RF and microwave packaging topics. Chapters provide detailed coverage of phased arrays, T/R modules, 3D transitions, high thermal conductivity materials, carbon nanotubes and graphene advanced materials, and chip size packaging for RF MEMS. It appeals to practicing engineers in the electronic packaging and high-frequency electronics domain, and to academic researchers interested in underst...

  14. 基于ARM的微波天线自动对准及跟踪控制系统的研究%Research on Microwave Antenna Automatic Aligning and Tracking Control System Based on ARM

    Institute of Scientific and Technical Information of China (English)

    官平; 夏兴海; 丁伟; 吴靓

    2012-01-01

    微波中继/接力通信通常采用高增益的微波天线.由于高增益微波天线方向性强,主波瓣角窄,因此,实现两站点间天线精确对准,保证通信质量,是一项困难而急需解决的问题.以自动控制技术、检测传感技术、精密传动技术以及GPS和电子罗盘技术为基础,研究设计了一套微波天线自动对准并跟踪保持的控制系统,经过在某通信系统上的实际使用,证明该系统结构紧凑、智能化程度高,稳定可靠.%The high gain microwave antenna is usually adopted in microwave relay communication. To ensure the quality of communication and achieve accurate alignment between the two stations antenna are difficult and urg - ent problem, because of the high gain microwave antenna directivity is strong,and the main lobe angle is narrow. The microwave antenna automatic alignment and tracking control system is researched,based on the automatic control technology, sensor detection technology, precision driving technology, GPS and lectronic compass tech - noloey. The system has the advantages of compact structure, high intrlli-gentiz degree, stable and reliable, which is used in the actual application.

  15. NOVEL MICROWAVE FILTER DESIGN TECHNIQUES.

    Science.gov (United States)

    ELECTROMAGNETIC WAVE FILTERS, MICROWAVE FREQUENCY, PHASE SHIFT CIRCUITS, BANDPASS FILTERS, TUNED CIRCUITS, NETWORKS, IMPEDANCE MATCHING , LOW PASS FILTERS, MULTIPLEXING, MICROWAVE EQUIPMENT, WAVEGUIDE FILTERS, WAVEGUIDE COUPLERS.

  16. The transverse magnetic field effect on steady-state solutions of the Bursian diode

    Energy Technology Data Exchange (ETDEWEB)

    Pramanik, Sourav; Chakrabarti, Nikhil [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Ender, A. Ya.; Kuznetsov, V. I. [Ioffe Institute, St. Petersburg 194021 (Russian Federation)

    2015-04-15

    A study of steady-states of a planar vacuum diode driven by a cold electron beam (the Bursian diode) under an external transverse magnetic field is presented. The regime of no electrons turned around by a magnetic field only is under the consideration. The emitter electric field is evaluated as a characteristic function for the existence of solutions depending on the diode length, the applied voltage, and the magnetic field strength. At certain conditions, it is shown that a region of non-unique solutions exists in the Bursian diode when the magnetic field is absent. An expression for the maximum current transmitted through the diode is derived. The external magnetic field is put forth to control fast electronic switches based on the Bursian diode.

  17. Angled stripe superluminescent diode

    Energy Technology Data Exchange (ETDEWEB)

    Figueroa, L.; Morrison, C.B.; Zinkiewicz, L.M.; Niesen, J.W.

    1989-08-08

    This patent describes a superluminescent light-emitting diode device having high power output and high spectral bandwidth. The device comprising: a semiconductor structure including at least one channel region formed in a semiconductor substrate and filled with a first semiconductor cladding layer of material having a higher index of refraction than substrate material outside the channel region, to provide lateral index-guiding of light within the channel region. The semiconductor structure also including a second semiconductor cladding layer of opposite conductivity type to the first, an active semiconductor layer at a junction between the first and second semiconductor cladding layers, and at least one emitting facet formed at a channel end; means for applying an electrical forward-bias voltage across the junction to produce emission of light; and wherein the channel is slightly inclined to a direction normal to the facet, to suppress lasing within the device, which can then operated at high powers and a broad spectral width.

  18. Particle size-controllable microwave-assisted solvothermal synthesis of the high-voltage cathode material LiCoPO4 using water/ethylene glycol solvent blends

    Science.gov (United States)

    Ludwig, Jennifer; Haering, Dominik; Doeff, Marca M.; Nilges, Tom

    2017-03-01

    Particle size-tuned platelets of the high-voltage cathode material LiCoPO4 for Li-ion batteries have been synthesized by a simple one-step microwave-assisted solvothermal process using an array of water/ethylene glycol (EG) solvent mixtures. Particle size control was achieved by altering the concentration of the EG co-solvent in the mixture between 0 and 100 vol%, with amounts of 0-80 vol% EG producing single phase, olivine-type LiCoPO4. The particle sizes of the olivine materials were significantly reduced from about 1.2 μm × 1.2 μm × 500 nm (0 vol% EG) to 200 nm × 100 nm × 50 nm (80 vol% EG) with increasing EG content, while specific surface areas increased from 2 to 13 m2 g-1. The particle size reduction could mainly be attributed to the modified viscosities of the solvent blends. Owing to the soft template effect of EG, the crystals exhibited the smallest dimensions along the [010] direction of the Li diffusion pathways in the olivine crystal structure, resulting in enhanced lithium diffusion properties. The relationship between the synthesis, crystal properties and electrochemical performance was further elucidated, indicating that the electrochemical performances of the as-prepared materials mainly depend on the solvent composition and the respective particle size range. LiCoPO4 products obtained from reaction media with low and high EG contents exhibited good electrochemical performances (initial discharge capacities of 87-124 mAh g-1 at 0.1 C), whereas materials made from medium EG concentrations (40-60 vol% EG) showed the highest capacities and gravimetric energy densities (up to 137 mAh g-1 and 658 Wh kg-1 at 0.1 C), excellent rate capabilities, and cycle life.

  19. Transmission-Type 2-Bit Programmable Metasurface for Single-Sensor and Single-Frequency Microwave Imaging

    Science.gov (United States)

    Li, Yun Bo; Li, Lian Lin; Xu, Bai Bing; Wu, Wei; Wu, Rui Yuan; Wan, Xiang; Cheng, Qiang; Cui, Tie Jun

    2016-03-01

    The programmable and digital metamaterials or metasurfaces presented recently have huge potentials in designing real-time-controlled electromagnetic devices. Here, we propose the first transmission-type 2-bit programmable coding metasurface for single-sensor and single- frequency imaging in the microwave frequency. Compared with the existing single-sensor imagers composed of active spatial modulators with their units controlled independently, we introduce randomly programmable metasurface to transform the masks of modulators, in which their rows and columns are controlled simultaneously so that the complexity and cost of the imaging system can be reduced drastically. Different from the single-sensor approach using the frequency agility, the proposed imaging system makes use of variable modulators under single frequency, which can avoid the object dispersion. In order to realize the transmission-type 2-bit programmable metasurface, we propose a two-layer binary coding unit, which is convenient for changing the voltages in rows and columns to switch the diodes in the top and bottom layers, respectively. In our imaging measurements, we generate the random codes by computer to achieve different transmission patterns, which can support enough multiple modes to solve the inverse-scattering problem in the single-sensor imaging. Simple experimental results are presented in the microwave frequency, validating our new single-sensor and single-frequency imaging system.

  20. Microwave-Mediated Green Synthesis of Silver Nanoparticles Using Ficus Elastica Leaf Extract and Application in Air Pollution Controlling Studies

    Directory of Open Access Journals (Sweden)

    N. Gandhi,

    2014-01-01

    Full Text Available Silver Nanoparticles are applied in various fields due to its anti bacterial properties. A conventional method for synthesis of AgNP requires dangerous chemical and large amount of energy is released in the process. Environmental friendly techniques are adopted for the synthesis of nanoparticles of silver. The present research work summarizes the green synthesis of silver nanoparticles by using leaf extract of Ficus Elastica and alternative energy sources micro wave irradiation. The synthesized Nanoparticles are characterized by uv- visible spectroscopy and by SEM. The synthesized nanoparticles are applied for controlling SO2 and NO2 from aqueous solution of SO2 and NO2. Batch adsorption studies are carried out. The effect of the temperature on adsorption of aqueous solution is studied at different temperature. A comparison of kinetic models applied to the adsorption of on silver Nanoparticles was evaluated for the pseudo first order, pseudo second order, Elovich and intraparticle diffusion models respectively. Results show that pseudo second order model was found to correlate the experimental data. Data fitted perfectly into and Freundlich adsorption isotherms.

  1. Terminal area automatic navigation, guidance and control research using the Microwave Landing System (MLS). Part 5: Design and development of a Digital Integrated Automatic Landing System (DIALS) for steep final approach using modern control techniques

    Science.gov (United States)

    Halyo, N.

    1983-01-01

    The design and development of a 3-D Digital Integrated Automatic Landing System (DIALS) for the Terminal Configured Vehicle (TCV) Research Aircraft, a B-737-100 is described. The system was designed using sampled data Linear Quadratic Gaussian (LOG) methods, resulting in a direct digital design with a modern control structure which consists of a Kalman filter followed by a control gain matrix, all operating at 10 Hz. DIALS uses Microwave Landing System (MLS) position, body-mounted accelerometers, as well as on-board sensors usually available on commercial aircraft, but does not use inertial platforms. The phases of the final approach considered are the localizer and glideslope capture which may be performed simultaneously, localizer and steep glideslope track or hold, crab/decrab and flare to touchdown. DIALS captures, tracks and flares from steep glideslopes ranging from 2.5 deg to 5.5 deg, selected prior to glideslope capture. Digital Integrated Automatic Landing System is the first modern control design automatic landing system successfully flight tested. The results of an initial nonlinear simulation are presented here.

  2. Performance evaluation of a lossy transmission lines based diode detector at cryogenic temperature

    Science.gov (United States)

    Villa, E.; Aja, B.; de la Fuente, L.; Artal, E.

    2016-01-01

    This work is focused on the design, fabrication, and performance analysis of a square-law Schottky diode detector based on lossy transmission lines working under cryogenic temperature (15 K). The design analysis of a microwave detector, based on a planar gallium-arsenide low effective Schottky barrier height diode, is reported, which is aimed for achieving large input return loss as well as flat sensitivity versus frequency. The designed circuit demonstrates good sensitivity, as well as a good return loss in a wide bandwidth at Ka-band, at both room (300 K) and cryogenic (15 K) temperatures. A good sensitivity of 1000 mV/mW and input return loss better than 12 dB have been achieved when it works as a zero-bias Schottky diode detector at room temperature, increasing the sensitivity up to a minimum of 2200 mV/mW, with the need of a DC bias current, at cryogenic temperature.

  3. Performance evaluation of a lossy transmission lines based diode detector at cryogenic temperature.

    Science.gov (United States)

    Villa, E; Aja, B; de la Fuente, L; Artal, E

    2016-01-01

    This work is focused on the design, fabrication, and performance analysis of a square-law Schottky diode detector based on lossy transmission lines working under cryogenic temperature (15 K). The design analysis of a microwave detector, based on a planar gallium-arsenide low effective Schottky barrier height diode, is reported, which is aimed for achieving large input return loss as well as flat sensitivity versus frequency. The designed circuit demonstrates good sensitivity, as well as a good return loss in a wide bandwidth at Ka-band, at both room (300 K) and cryogenic (15 K) temperatures. A good sensitivity of 1000 mV/mW and input return loss better than 12 dB have been achieved when it works as a zero-bias Schottky diode detector at room temperature, increasing the sensitivity up to a minimum of 2200 mV/mW, with the need of a DC bias current, at cryogenic temperature.

  4. The Cosmic Microwave Background

    OpenAIRE

    Silk, Joseph

    2002-01-01

    This set of lectures provides an overview of the basic theory and phenomenology of the cosmic microwave background. Topics include a brief historical review; the physics of temperature and polarization fluctuations; acoustic oscillations of the primordial plasma; the space of inflationary cosmological models; current and potential constraints on these models from the microwave background; and constraints on inflation.

  5. Microwave Enhanced Reactive Distillation

    NARCIS (Netherlands)

    Altman, E.

    2011-01-01

    The application of electromagnetic irradiation in form of microwaves (MW) has gathered the attention of the scientific community in recent years. MW used as an alternative energy source for chemical syntheses (microwave chemistry) can provide clear advantages over conventional heating methods in ter

  6. Use of microwave in processing of drug delivery systems.

    Science.gov (United States)

    Wong, T W

    2008-04-01

    Microwave has received a widespread application in pharmaceuticals and food processing, microbial sterilization, biomedical therapy, scientific and biomedical analysis, as well as, drug synthesis. This paper reviews the basis of application of microwave to prepare pharmaceutical dosage forms such as agglomerates, gel beads, microspheres, nanomatrix, solid dispersion, tablets and film coat. The microwave could induce drying, polymeric crosslinkages as well as drug-polymer interaction, and modify the structure of drug crystallites via its effects of heating and/or electromagnetic field on the dosage forms. The use of microwave opens a new approach to control the physicochemical properties and drug delivery profiles of pharmaceutical dosage forms without the need for excessive heat, lengthy process or toxic reactants. Alternatively, the microwave can be utilized to process excipients prior to their use in the formulation of drug delivery systems. The intended release characteristics of drugs in dosage forms can be met through modifying the physicochemical properties of excipients using the microwave.

  7. Diode-pumped dye laser

    Science.gov (United States)

    Burdukova, O. A.; Gorbunkov, M. V.; Petukhov, V. A.; Semenov, M. A.

    2016-10-01

    This letter reports diode pumping for dye lasers. We offer a pulsed dye laser with an astigmatism-compensated three-mirror cavity and side pumping by blue laser diodes with 200 ns pulse duration. Eight dyes were tested. Four dyes provided a slope efficiency of more than 10% and the highest slope efficiency (18%) was obtained for laser dye Coumarin 540A in benzyl alcohol.

  8. MMIC Replacement for Gunn Diode Oscillators

    Science.gov (United States)

    Crowe, Thomas W.; Porterfield, David

    2011-01-01

    An all-solid-state replacement for high-frequency Gunn diode oscillators (GDOs) has been proposed for use in NASA s millimeter- and submillimeter-wave sensing instruments. Highly developed microwave oscillators are used to achieve a low-noise and highly stable reference signal in the 10-40-GHz band. Compact amplifiers and high-power frequency multipliers extend the signal to the 100-500-GHz band with minimal added phase noise and output power sufficient for NASA missions. This technology can achieve improved output power and frequency agility, while maintaining phase noise and stability comparable to other GDOs. Additional developments of the technology include: a frequency quadrupler to 145 GHz with 18 percent efficiency and 15 percent fixed tuned bandwidth; frequency doublers featuring 124, 240, and 480 GHz; an integrated 874-GHz subharmonic mixer with a mixer noise temperature of 3,000 K DSB (double sideband) and mixer conversion loss of 11.8 dB DSB; a high-efficiency frequency tripler design with peak output power of 23 mW and 14 mW, and efficiency of 16 and 13 percent, respectively; millimeter-wave integrated circuit (MMIC) power amplifiers to the 30-40 GHz band with high DC power efficiency; and an 874-GHz radiometer suitable for airborne observation with state-of-the-art sensitivity at room temperature and less than 5 W of total power consumption.

  9. Computer Processing Of Tunable-Diode-Laser Spectra

    Science.gov (United States)

    May, Randy D.

    1991-01-01

    Tunable-diode-laser spectrometer measuring transmission spectrum of gas operates under control of computer, which also processes measurement data. Measurements in three channels processed into spectra. Computer controls current supplied to tunable diode laser, stepping it through small increments of wavelength while processing spectral measurements at each step. Program includes library of routines for general manipulation and plotting of spectra, least-squares fitting of direct-transmission and harmonic-absorption spectra, and deconvolution for determination of laser linewidth and for removal of instrumental broadening of spectral lines.

  10. Effect of microwave power on kinetics and characteristics of microwave vacuum-dried longan (Dimocarpus longan Lour.) pulp.

    Science.gov (United States)

    Su, Dongxiao; Zhang, Mingwei; Wei, Zhencheng; Tang, Xiaojun; Zhang, Ruifen; Liu, Lei; Deng, Yuanyuan

    2015-03-01

    The drying kinetics of longan (Dimocarpus longan Lour.) pulp processed by microwave vacuum under different microwave levels (2.67, 5.33, 8.00, and 10.67 W/g) was investigated (pressure controlled at -85 ± 2 kPa) in the present study. It was found that the drying rate of longan pulp was dependent on the microwave power, and the rehydration rate increased from 1.96 to 2.17 with the increase of microwave power from 2.67 to 10.67 W/g. Among nine selected thin layer models, the microwave vacuum drying of longan pulp was well represented by five models, which were Page, Modified Henderson and Pabis, Wang and Singh, Logarithmic, and Midilli models. Furthermore, the results of statistical analysis indicated that the Midilli model could describe the best experimental data. In addition, scanning electron microscope observation showed that the microwave vacuum-dried longan pulp had a porous structure.

  11. The microwave absorption of ceramic-cup microwave ion source

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An experiment system of ceramic-cup microwave ion source has been built here. Its microwave absorption efficiency as a function of the magnetic field and the pressure is presented. When the microwave incident power is 300~500W the microwave absorption efficiencies are more than 90% if the system is optimized and the magnetic field at the microwave window is 0.095T.

  12. Farinon microwave end of life cycle

    Energy Technology Data Exchange (ETDEWEB)

    Poe, R.C.

    1996-06-24

    This engineering report evaluates alternatives for the replacement of the Farinon microwave radio system. The system is beyond its expected life cycle and has decreasing maintainability. Principal applications supported by the Farinon system are two electrical utility monitor and control systems, the Integrated Transfer Trip System (ITTS), and the Supervisory Control and Data Acquisition (SCADA) system.

  13. The Effect of Diode Laser With Different Parameters on Root Fracture During Irrigation Procedure.

    Science.gov (United States)

    Karataş, Ertuğrul; Arslan, Hakan; Topçuoğlu, Hüseyin Sinan; Yılmaz, Cenk Burak; Yeter, Kübra Yesildal; Ayrancı, Leyla Benan

    2016-06-01

    The aim of this study is to compare the effect of a single diode laser application and agitation of EDTA with diode laser with different parameters at different time intervals on root fracture. Ninety mandibular incisors were instrumented except the negative control group. The specimens were divided randomly into 10 groups according to final irrigation procedure: (G1) non-instrumented; (G2) distilled water; (G3) 15% EDTA; (G4) ultrasonically agitated EDTA; (G5) single 1.5W/100 Hz Diode laser; (G6) single 3W/100 Hz Diode laser; (G7) 1.5W/100 Hz Diode laser agitation of EDTA for 20 s; (G8) 1.5W/100 Hz Diode laser agitation of EDTA for 40 s; (G9) 3W/100 Hz Diode laser agitation of EDTA for 20 s; and (G10) 3W/100 Hz Diode laser agitation of EDTA for 40 s. The specimens were filled, mounted in acrylic resin, and compression strength test was performed on each specimen. Statistical analysis was carried out using one way ANOVA and Tukey's post hoc tests (P = 0.05). The statistical analysis revealed that there were statistically significant differences among the groups (P irrigation with a 3W/100 Hz Diode laser for both 20 s and 40 s decreased the fracture resistance of teeth.

  14. Microwave gain medium with negative refractive index.

    Science.gov (United States)

    Ye, Dexin; Chang, Kihun; Ran, Lixin; Xin, Hao

    2014-12-19

    Artificial effective media are attractive because of the fantastic applications they may enable, such as super lensing and electromagnetic invisibility. However, the inevitable loss due to their strongly dispersive nature is one of the fundamental challenges preventing such applications from becoming a reality. In this study, we demonstrate an effective gain medium based on negative resistance, to overcompensate the loss of a conventional passive metamaterial, meanwhile keeping its original negative-index property. Energy conservation-based theory, full-wave simulation and experimental measurement show that a fabricated sample consisting of conventional sub-wavelength building blocks with embedded microwave tunnel diodes exhibits a band-limited Lorentzian dispersion simultaneously with a negative refractive index and a net gain. Our work provides experimental evidence to the assertion that a stable net gain in negative-index gain medium is achievable, proposing a potential solution for the critical challenge current metamateiral technology faces in practical applications.

  15. Microwave gain medium with negative refractive index

    Science.gov (United States)

    Ye, Dexin; Chang, Kihun; Ran, Lixin; Xin, Hao

    2014-12-01

    Artificial effective media are attractive because of the fantastic applications they may enable, such as super lensing and electromagnetic invisibility. However, the inevitable loss due to their strongly dispersive nature is one of the fundamental challenges preventing such applications from becoming a reality. In this study, we demonstrate an effective gain medium based on negative resistance, to overcompensate the loss of a conventional passive metamaterial, meanwhile keeping its original negative-index property. Energy conservation-based theory, full-wave simulation and experimental measurement show that a fabricated sample consisting of conventional sub-wavelength building blocks with embedded microwave tunnel diodes exhibits a band-limited Lorentzian dispersion simultaneously with a negative refractive index and a net gain. Our work provides experimental evidence to the assertion that a stable net gain in negative-index gain medium is achievable, proposing a potential solution for the critical challenge current metamateiral technology faces in practical applications.

  16. Integrating an Embedded System within a Microwave Moisture Meter

    Science.gov (United States)

    In this paper, the conversion of a PC or laptop-controlled microwave moisture meter to a stand-alone meter hosting its own embedded system is discussed. The moisture meter uses low-power microwaves to measure the attenuation and phase shift of the sample, from which the dielectric properties are cal...

  17. Integrating an embedded system in a microwave moisture meter

    Science.gov (United States)

    The conversion of a PC- or laptop-controlled microwave moisture meter to a stand-alone meter hosting its own embedded system is discussed. The moisture meter measures the attenuation and phase shift of low power microwaves traversing the sample, from which the dielectric properties are calculated. T...

  18. Frequency division multiplexed microwave and baseband digital optical fiber link for phased array antennas

    Science.gov (United States)

    Heim, Peter J.; McClay, C. Phillip

    1990-05-01

    A frequency-division multiplexed optical fiber link is described in which microwave (1-8 GHz) and baseband digital (1-10 Mb/s) signals are combined electrically and transmitted through a direct-modulation microwave optical link. The microwave signal does not affect bit error rate (BER) performance of the Manchester-coded baseband digital data link. The baseband digital signal affects microwave signal quality by generating second-order intermodulation noise. The intermodulation noise power density is found to be proportional to both the microwave input power and the digital input power, enabling the system to be modeled as a mixer (AM modulator). The conversion loss for the digital signal is approximately 68 dB for a 1-GHz microwave signal and is highly dependent on the microwave frequency, reaching a minimum value of 41 dB at 4.5 GHz, corresponding to the laser diode relaxation oscillation frequency. It is shown that Manchester coding on the digital link places the intermodulation noise peak away from the microwave signal, preventing degradation of close-carrier phase noise (<1 kHz offset). A direct trade-off between intermodulation noise and digital link margin is developed to project system performance.

  19. Gold Nanoparticle Microwave Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Krantz, Kelsie E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Christian, Jonathan H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Coopersmith, Kaitlin [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Washington, II, Aaron L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Murph, Simona H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-07-27

    At the nanometer scale, numerous compounds display different properties than those found in bulk material that can prove useful in areas such as medicinal chemistry. Gold nanoparticles, for example, display promise in newly developed hyperthermia therapies for cancer treatment. Currently, gold nanoparticle synthesis is performed via the hot injection technique which has large variability in final particle size and a longer reaction time. One underdeveloped area by which these particles could be produced is through microwave synthesis. To initiate heating, microwaves agitate polar molecules creating a vibration that gives off the heat energy needed. Previous studies have used microwaves for gold nanoparticle synthesis; however, polar solvents were used that partially absorbed incident microwaves, leading to partial thermal heating of the sample rather than taking full advantage of the microwave to solely heat the gold nanoparticle precursors in a non-polar solution. Through this project, microwaves were utilized as the sole heat source, and non-polar solvents were used to explore the effects of microwave heating only as pertains to the precursor material. Our findings show that the use of non-polar solvents allows for more rapid heating as compared to polar solvents, and a reduction in reaction time from 10 minutes to 1 minute; this maximizes the efficiency of the reaction, and allows for reproducibility in the size/shape of the fabricated nanoparticles.

  20. Gold Nanoparticle Microwave Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Krantz, Kelsie E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Christian, Jonathan H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Coopersmith, Kaitlin [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Washington, II, Aaron L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Murph, Simona H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-07-27

    At the nanometer scale, numerous compounds display different properties than those found in bulk material that can prove useful in areas such as medicinal chemistry. Gold nanoparticles, for example, display promise in newly developed hyperthermia therapies for cancer treatment. Currently, gold nanoparticle synthesis is performed via the hot injection technique which has large variability in final particle size and a longer reaction time. One underdeveloped area by which these particles could be produced is through microwave synthesis. To initiate heating, microwaves agitate polar molecules creating a vibration that gives off the heat energy needed. Previous studies have used microwaves for gold nanoparticle synthesis; however polar solvents were used that partially absorbed incident microwaves, leading to partial thermal heating of the sample rather than taking full advantage of the microwave to solely heat the gold nanoparticle precursors in a non-polar solution. Through this project, microwaves were utilized as the sole heat source, and non-polar solvents were used to explore the effects of microwave heating only as pertains to the precursor material. Our findings show that the use of non-polar solvents allows for more rapid heating as compared to polar solvents, a reduction in reaction time from 10 minutes to 1 minute, maximizes the efficiency of the reaction, and allows for reproducibility in the size/shape of the fabricated nanoparticles.

  1. Light Emitting Diodes (LEDs)

    Science.gov (United States)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique, called Photodynamic Therapy, requires the surgeon to use tiny, pinhead-size Light Emitting Diodes (LEDs) (a source that releases long wavelengths of light ) to activate light-sensitive, tumor-treating drugs. 'A young woman operated on in May 1999 has fully recovered with no complications and no evidence of the tumor coming back,' said Dr. Harry Whelan, a pediatric neurologist at the Medical Hospital of Wisconsin in Milwaukee. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can be used for hours at a time while still remaining cool to the touch. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The LEDs, developed and managed by NASA's Marshall Space Flight Center, have been used on seven Space Shuttle flights inside the Microgravity Astroculture Facility. This technology has also been successfully used to further commercial research in crop growth.

  2. Advances in microwaves 4

    CERN Document Server

    Young, Leo

    2013-01-01

    Advances in Microwaves, Volume 4 covers some innovations in the devices and applications of microwaves. This volume contains three chapters and begins with a discussion of the application of microwave phasers and time delay elements as beam steering elements in array radars. The next chapter provides first an overview of the technical aspects and different types of millimeter waveguides, followed by a survey of their application to railroads. The last chapter examines the general mode of conversion properties of nonuniform waveguides, such as waveguide tapers, using converted Maxwell's equatio

  3. Integrated microwave photonics

    CERN Document Server

    Marpaung, David; Heideman, Rene; Leinse, Arne; Sales, Salvador; Capmany, Jose

    2012-01-01

    Microwave photonics (MWP) is an emerging field in which radio frequency (RF) signals are generated, distributed, processed and analyzed using the strength of photonic techniques. It is a technology that enables various functionalities which are not feasible to achieve only in the microwave domain. A particular aspect that recently gains significant interests is the use of photonic integrated circuit (PIC) technology in the MWP field for enhanced functionalities and robustness as well as the reduction of size, weight, cost and power consumption. This article reviews the recent advances in this emerging field which is dubbed as integrated microwave photonics. Key integrated MWP technologies are reviewed and the prospective of the field is discussed.

  4. The Microwave Hall Effect

    OpenAIRE

    2015-01-01

    This paper describes a simple microwave apparatus to measure the Hall effect in semiconductor wafers. The advantage of this technique is that it does not require contacts on the sample or the use of a resonant cavity. Our method consists of placing the semiconductor wafer into a slot cut in an X-band (8 - 12 GHz) waveguide series tee, injecting microwave power into the two opposite arms of the tee, and measuring the microwave output at the third arm. A magnetic field applied perpendicular to ...

  5. Monolithic microwave integrated circuits

    Science.gov (United States)

    Pucel, R. A.

    Monolithic microwave integrated circuits (MMICs), a new microwave technology which is expected to exert a profound influence on microwave circuit designs for future military systems as well as for the commercial and consumer markets, is discussed. The book contains an historical discussion followed by a comprehensive review presenting the current status in the field. The general topics of the volume are: design considerations, materials and processing considerations, monolithic circuit applications, and CAD, measurement, and packaging techniques. All phases of MMIC technology are covered, from design to testing.

  6. Equipment Design of Camellia Fruit and Shell Separating by Micro-wave

    Directory of Open Access Journals (Sweden)

    Jian Zhou

    2015-07-01

    Full Text Available For obtaining excellent properties of separating Camellia fruit and shell, the micro-wave technology is used, the separating equipment is also designed. The set includes lifting raw material system, micro-wave controlling system, eliminating wet system, micro-wave affection body, dropping material system. The camellia fruits are transported into micro-wave system, then they are crashed with centrifugal throwing disc, by the affect of wind and centrifugal force, thus shells and seeds are separated obviously.

  7. Microwave Technologies as Part of an Integrated Weed Management Strategy: A Review

    OpenAIRE

    Graham Brodie; Carmel Ryan; Carmel Lancaster

    2012-01-01

    Interest in controlling weed plants using radio frequency or microwave energy has been growing in recent years because of the growing concerns about herbicide resistance and chemical residues in the environment. This paper reviews the prospects of using microwave energy to manage weeds. Microwave energy effectively kills weed plants and their seeds; however, most studies have focused on applying the microwave energy over a sizable area, which requires about ten times the energy that is embodi...

  8. Spin-torque diode with tunable sensitivity and bandwidth by out-of-plane magnetic field

    Science.gov (United States)

    Li, X.; Zheng, C.; Zhou, Y.; Kubota, H.; Yuasa, S.; Pong, Philip W. T.

    2016-06-01

    Spin-torque diodes based on nanosized magnetic tunnel junctions are novel microwave detectors with high sensitivity and wide frequency bandwidth. While previous reports mainly focus on improving the sensitivity, the approaches to extend the bandwidth are limited. This work experimentally demonstrates that through optimizing the orientation of the external magnetic field, wide bandwidth can be achieved while maintaining high sensitivity. The mechanism of the frequency- and sensitivity-tuning is investigated through analyzing the dependence of resonant frequency and DC voltage on the magnitude and the tilt angle of hard-plane magnetic field. The frequency dependence is qualitatively explicated by Kittel's ferromagnetic resonance model. The asymmetric resonant frequency at positive and negative magnetic field is verified by the numerical simulation considering the in-plane anisotropy. The DC voltage dependence is interpreted through evaluating the misalignment angle between the magnetization of the free layer and the reference layer. The tunability of the detector performance by the magnetic field angle is evaluated through characterizing the sensitivity and bandwidth under 3D magnetic field. The frequency bandwidth up to 9.8 GHz or maximum sensitivity up to 154 mV/mW (after impedance mismatch correction) can be achieved by tuning the angle of the applied magnetic field. The results show that the bandwidth and sensitivity can be controlled and adjusted through optimizing the orientation of the magnetic field for various applications and requirements.

  9. Composite resonator vertical cavity laser diode

    Energy Technology Data Exchange (ETDEWEB)

    Choquette, K.D.; Hou, H.Q.; Chow, W.W.; Geib, K.M.; Hammons, B.E.

    1998-05-01

    The use of two coupled laser cavities has been employed in edge emitting semiconductor lasers for mode suppression and frequency stabilization. The incorporation of coupled resonators within a vertical cavity laser opens up new possibilities due to the unique ability to tailor the interaction between the cavities. Composite resonators can be utilized to control spectral and temporal properties within the laser; previous studies of coupled cavity vertical cavity lasers have employed photopumped structures. The authors report the first composite resonator vertical cavity laser diode consisting of two optical cavities and three monolithic distributed Bragg reflectors. Cavity coupling effects and two techniques for external modulation of the laser are described.

  10. Demonstration and experimental evaluation of a bi-directional 10-GHz microwave photonic filter

    Science.gov (United States)

    Zaldívar-Huerta, I. E.; Correa-Mena, A. G.; Hernández-Nava, P.; García-Juárez, A.; Rodríguez-Asomoza, J.; Lee, Min Won

    2016-09-01

    A bi-directional 10-GHz microwave photonic filter is proposed and experimentally evaluated. Its frequency response consists of a series of microwave band-pass windows obtained by the interaction of externally modulated multimode laser diodes emitting around of 1550 nm associated to the chromatic dispersion parameter of an optical fiber, as well as the length of the optical link. Microwave band-pass windows exhibit on average a-3 dB bandwidth of 378 MHz. This electro-optical system shows an efficient configuration and good performance. Potentially, filtered microwave signals can be used as electrical carriers in optical communication systems to transmit and distribute services such as video, voice and data.

  11. Variable Power, Short Microwave Pulses Generation using a CW Magnetron

    Directory of Open Access Journals (Sweden)

    CIUPA, R.

    2011-05-01

    Full Text Available Fine control of microwave power radiation in medical and scientific applications is a challenging task. Since a commercial Continuous Wave (CW magnetron is the most inexpensive microwave device available today on the market, it becomes the best candidate for a microwave power generator used in medical diathermy and hyperthermia treatments or high efficiency chemical reactions using microwave reactors as well. This article presents a new method for driving a CW magnetron with short pulses, using a modified commercial Zero Voltage Switching (ZVS inverter, software driven by a custom embedded system. The microwave power generator designed with this method can be programmed for output microwave pulses down to 1% of the magnetron's power and allows microwave low frequency pulse modulation in the range of human brain electrical activity, intended for medical applications. Microwave output power continuous control is also possible with the magnetron running in the oscillating area, using a dual frequency Pulse Width Modulation (PWM, where the low frequency PWM pulse is modulating a higher resonant frequency required by the ZVS inverter's transformer. The method presented allows a continuous control of both power and energy (duty-cycle at the inverter's output.

  12. Magnesium-doped zinc oxide nanorod-nanotube semiconductor/p-silicon heterojunction diodes

    Science.gov (United States)

    Caglar, Yasemin; Görgün, Kamuran; Ilican, Saliha; Caglar, Mujdat; Yakuphanoğlu, Fahrettin

    2016-08-01

    Nanostructured zinc oxide material is usable in electronic device applications such as light-emitting diodes, heterojunction diode, sensors, solar cell due to its interesting electrical conductivity and optical properties. Magnesium-doped zinc oxide nanorod (NR)-nanotube (NT) films were grown by microwave-assisted chemical bath deposition to fabricate ZnO-based heterojunction diode. It is found that ZnO hexagonal nanorods turn into hexagonal nanotubes when the Mg doping ratio is increased from 1 to 10 %. The values of the optical band gap for 1 % Mg-doped ZnO NR and 10 % Mg-doped ZnO NT films are found to be 3.14 and 3.22 eV, respectively. The n-ZnO:Mg/p-Si heterojunction diodes were fabricated. The diodes exhibited a rectification behavior with ideality factor higher than unity due to the presence of surface states in the junction and series resistance. The obtained results indicate that Mg doping improves the electrical and optical properties of ZnO.

  13. Microwave Service Towers

    Data.gov (United States)

    Department of Homeland Security — This file is an extract of the Universal Licensing System (ULS) licensed by the Wireless Telecommunications Bureau (WTB). It consists of Microwave Transmitters (see...

  14. Microwave Radiometer Profiler

    Data.gov (United States)

    Oak Ridge National Laboratory — The microwave radiometer profiler (MWRP) provides vertical profiles of temperature, humidity, and cloud liquid water content as a function of height or pressure at...

  15. Microwave Oven Observations.

    Science.gov (United States)

    Sumrall, William J.; Richardson, Denise; Yan, Yuan

    1998-01-01

    Explains a series of laboratory activities which employ a microwave oven to help students understand word problems that relate to states of matter, collect data, and calculate and compare electrical costs to heat energy costs. (DDR)

  16. Microwave Oven Observations.

    Science.gov (United States)

    Sumrall, William J.; Richardson, Denise; Yan, Yuan

    1998-01-01

    Explains a series of laboratory activities which employ a microwave oven to help students understand word problems that relate to states of matter, collect data, and calculate and compare electrical costs to heat energy costs. (DDR)

  17. Microwave Radiometer - high frequency

    Data.gov (United States)

    Oak Ridge National Laboratory — The Microwave Radiometer-High Frequency (MWRHF) provides time-series measurements of brightness temperatures from two channels centered at 90 and 150 GHz. These two...

  18. Low-Level Laser and Light-Emitting Diode Therapy for Pain Control in Hyperglycemic and Normoglycemic Patients Who Underwent Coronary Bypass Surgery with Internal Mammary Artery Grafts: A Randomized, Double-Blind Study with Follow-Up.

    Science.gov (United States)

    Lima, Andréa Conceição Gomes; Fernandes, Gilderlene Alves; Gonzaga, Isabel Clarisse; de Barros Araújo, Raimundo; de Oliveira, Rauirys Alencar; Nicolau, Renata Amadei

    2016-06-01

    This study aimed to evaluate the efficacy of low-level laser therapy (LLLT) and light-emitting diodes (LEDs) for reducing pain in hyperglycemic and normoglycemic patients who underwent coronary artery bypass surgery with internal mammary artery grafts. This study was conducted on 120 volunteers who underwent elective coronary artery bypass graft (CABG) surgery. The volunteers were randomly allocated to four different groups of equal size (n = 30): control, placebo, LLLT [λ = 640 nm and spatial average energy fluence (SAEF) = 1.06 J/cm(2)], and LED (λ = 660 ± 20 nm and SAEF = 0.24 J/cm(2)). Participants were also divided into hyperglycemic and normoglycemic subgroups, according to their fasting blood glucose test result before surgery. The outcome assessed was pain during coughing by a visual analog scale (VAS) and the McGill Pain Questionnaire. The patients were followed for 1 month after the surgery. The LLLT and LED groups showed a greater decrease in pain, with similar results, as indicated by both the VAS and the McGill questionnaire (p ≤ 0.05), on the 6th and 8th postoperative day compared with the placebo and control groups. The outcomes were also similar between hyperglycemic and normoglycemic patients. One month after the surgery, almost no individual reported pain during coughing. LLLT and LED had similar analgesic effects in hyperglycemic and normoglycemic patients, better than placebo and control groups.

  19. Microwave workshop for Windows

    Directory of Open Access Journals (Sweden)

    Colin White

    1995-12-01

    Full Text Available A suite of three programs has been developed to support the teaching of microwave theory and design. A secondary function of the package is to support microwave engineers by providing a library of utilities to assist their design function. All three programs were written in Visual Basic and are aimed at supporting both tutor-directed and student-centred learning methodologies. The development team consisted of three final-year degree students.

  20. Microwave system engineering principles

    CERN Document Server

    Raff, Samuel J

    1977-01-01

    Microwave System Engineering Principles focuses on the calculus, differential equations, and transforms of microwave systems. This book discusses the basic nature and principles that can be derived from thermal noise; statistical concepts and binomial distribution; incoherent signal processing; basic properties of antennas; and beam widths and useful approximations. The fundamentals of propagation; LaPlace's Equation and Transmission Line (TEM) waves; interfaces between homogeneous media; modulation, bandwidth, and noise; and communications satellites are also deliberated in this text. This bo

  1. Diode laser power module for beamed power transmission

    Science.gov (United States)

    Choi, S. H.; Williams, M. D.; Lee, J. H.; Conway, E. J.

    1991-01-01

    Recent progress with powerful, efficient, and coherent monolithic diode master-oscillator/power-amplifier (M-MOPA) systems is promising for the development of a space-based diode laser power station. A conceptual design of a 50-kW diode laser power module was made for space-based power stations capable of beaming coherent power to the moon, Martian rovers, or other satellites. The laser diode power module consists of a solar photovoltaic array or nuclear power source, diode laser arrays (LDAs), a phase controller, beam-steering optics, a thermal management unit, and a radiator. Thermal load management and other relevant aspects of the system (such as power requirements and system mass) are considered. The 50-kW power module described includes the highest available efficiency of LD M-MOPA system to date. However, the overall efficiency of three amplifier stages, including the coupling efficiency, turns out to be 55.5 percent. Though a chain of PA stages generates a high-power coherent beam, there is a penalty due to the coupling loss between stages. The specific power of the 50-kW module using solar power is 6.58 W/kg.

  2. Laser Diode Beam Basics, Manipulations and Characterizations

    CERN Document Server

    Sun, Haiyin

    2012-01-01

    Many optical design technical books are available for many years which mainly deal with image optics design based on geometric optics and using sequential raytracing technique. Some books slightly touched laser beam manipulation optics design. On the other hand many books on laser diodes have been published that extensively deal with laser diode physics with little touching on laser diode beam manipulations and characterizations. There are some internet resources dealing with laser diode beams. However, these internet resources have not covered enough materials with enough details on laser diode beam manipulations and characterizations. A technical book concentrated on laser diode beam manipulations and characterizations can fit in to the open and provide useful information to laser diode users. Laser Diode Beam Basics, Manipulations and  Characterizations is concentrated on the very practical side of the subject, it only discusses the basic physics and mathematics that are necessary for the readers in order...

  3. Three-phase bridge rectifiers with freewheeling diodes

    CERN Document Server

    Hausler, M

    1973-01-01

    Freewheeling diodes are used in controlled rectifiers working in one quadrant only in order to reduce the reactive power and the d.c.- voltage ripple. In addition the freewheeling diodes allow a higher d.c.-current at low d.c.-voltages. The mean value of the freewheeling current depends on the d.c.-current, the load, and the stray-reactance of the rectifier transformer. This paper describes how the freewheeling current can be determined with these parameters. Results for some typical cases are shown in diagrams. (2 refs).

  4. System and method for high power diode based additive manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    El-Dasher, Bassem S.; Bayramian, Andrew; Demuth, James A.; Farmer, Joseph C.; Torres, Sharon G.

    2016-04-12

    A system is disclosed for performing an Additive Manufacturing (AM) fabrication process on a powdered material forming a substrate. The system may make use of a diode array for generating an optical signal sufficient to melt a powdered material of the substrate. A mask may be used for preventing a first predetermined portion of the optical signal from reaching the substrate, while allowing a second predetermined portion to reach the substrate. At least one processor may be used for controlling an output of the diode array.

  5. Theory of piezo-phototronics for light-emitting diodes.

    Science.gov (United States)

    Zhang, Yan; Wang, Zhong Lin

    2012-09-04

    Devices fabricated by using the inner-crystal piezopotential as a "gate" voltage to tune/control the carrier generation, transport, and recombination processes at the vicinity of a p-n junction are named piezo-phototronics. Here, the theory of the photon emission and carrier transport behavior in piezo-phototronic devices is investigated as a p-n junction light-emitting diode. Numerical calculations are given for predicting the photon emission and current-voltage characteristics of a general piezo-phototronic light-emitting diode.

  6. DESIGN OF THE TESTING AND CONTROL APPARATUS FOR EQUIPMENT USED IN MICROWAVE-SWITCH’S LONGEVITY VALIDATION%微波开关寿命试验设备的测控仪设计

    Institute of Scientific and Technical Information of China (English)

    魏广; 马少君; 陈联; 李元明

    2015-01-01

    This paper mainly introduced the design of The testing and control apparatus for equipment used in micro-wave-switch’ s longevity validation. The testing and control apparatus can remote control and collect data of microwave-switch,control vacuum pumps and heaters on the equipment,measure the pressure and temperature in the vacuum,and of-fer human-computer interface. The testing and control apparatus can also protect the microwave-switch from fault mode. The central processing unit of the apparatus is the DSP system,which achieve all the Real-time control and testing. The hu-man-computer interface is provided by a Touch Control integrative Machine,which can receive and display the data and save them.%主要介绍了微波开关寿命试验设备中测控仪的设计。测控仪的主要功能是实现对微波开关的控制指令传送、状态遥测参数采集,对试验设备的各种真空泵、加热器进行控制,实现真空室压力、温度的采集与控制,并提供相关的人机交互界面,完成非正常情况的保护处理等。测控仪的设计采用了TI公司的DSP组成核心控制单元,实现参数的实时控制和采集;采用WINCE触控一体机提供人机交互界面,实现通讯数据的接收、显示、及数据存储。

  7. Orthodontic instrument sterilization with microwave irradiation

    Directory of Open Access Journals (Sweden)

    Arif Yezdani

    2015-01-01

    Full Text Available Objective: This study was designed to evaluate the efficiency of microwave sterilization of orthodontic instruments and molar bands immersed in plain distilled water with and without oral rinse, and to ascertain the minimum time of exposure required to sterilize. Materials and Methods: The orthodontic instruments (hinged and nonhinged, molar bands and mouth mirrors used in the patient′s mouth were selected for the study. The instruments were divided into two groups - Group I with oral rinse-set A (0.01% chlorhexidine gluconate and set B (0.025% betadine and Group II (included sets C and D without oral rinse. The instruments of set A, B and C were microwaved at 2,450 MHz, 800 W for 5 min, whereas, set D was microwaved for 10 min at the same above mentioned specifications. The efficacy of sterilization was assessed by stab inoculation of the instruments onto trypticase soya agar plates. The plates were checked for bacterial growth following incubation at 37°C for 24 h. For sterility control, Geobacillus stearothermophilus (MTCC 1518 was included. Results: No growth was observed in the plates that were inoculated with the microwaved orthodontic instruments of sets A, B and D, whereas scanty bacterial growth was observed in the plates inoculated with the microwaved set C instruments. Conclusion: Effective sterilization was achieved when the orthodontic instruments and molar bands were immersed in distilled water without oral rinse and microwaved for 10 min as also for those that were immersed in distilled water with oral rinse and microwaved for 5 min.

  8. Thin conformal antenna array for microwave power conversions

    Science.gov (United States)

    Dickinson, R. M. (Inventor)

    1978-01-01

    A structure of a circularly polarized, thin conformal, antenna array which may be mounted integrally with the skin of an aircraft employs microstrip elliptical elements and interconnecting feed lines spaced from a circuit ground plane by a thin dielectric layer. The feed lines are impedance matched to the elliptical antenna elements by selecting a proper feedpoint inside the periphery of the elliptical antenna elements. Diodes connected between the feed lines and the ground plane rectify the microwave power, and microstrip filters (low pass) connected in series with the feed lines provide dc current to a microstrip bus. Low impedance matching strips are included between the elliptical elements and the rectifying and filtering elements.

  9. Characteristics of frozen colostrum thawed in a microwave oven

    Energy Technology Data Exchange (ETDEWEB)

    Jones, L.R.; Taylor, A.W.; Hines, H.C.

    1987-09-01

    Use of a microwave oven to thaw frozen colostrum was evaluated. Colostrum was collected from nine cows, four of which were immunized to produce specific colostral antibodies. Colostrum from each cow was frozen, subsequently thawed, and pooled. One-liter aliquots of the pooled colostrum were frozen and assigned randomly to three thawing treatments. Colostrum was thawed using one of three regimens: 10 min in a microwave oven at full power (650 W), 17 min in a microwave oven at half power (325 W), and 25 min in 45 degrees C water. Colostrum thawed in the microwave oven was slightly coagulated and had lower volume and total protein content than colostrum thawed in water. Casein and pH were not different among treatments. Both concentration and total content of immunoglobulin A were higher in the control than in microwave treatments. Neither amount nor concentration of immunoglobulin G and immunoglobulin M were different among treatments. Immunological activity, measured by a hemolytic test, was lower for microwave treatments than the control but did not differ between microwave treatments. Frozen colostrum thawed in a microwave oven should provide a reasonable source of colostrum when fresh high quality colostrum is not available.

  10. Microwave Technologies as Part of an Integrated Weed Management Strategy: A Review

    Directory of Open Access Journals (Sweden)

    Graham Brodie

    2012-01-01

    Full Text Available Interest in controlling weed plants using radio frequency or microwave energy has been growing in recent years because of the growing concerns about herbicide resistance and chemical residues in the environment. This paper reviews the prospects of using microwave energy to manage weeds. Microwave energy effectively kills weed plants and their seeds; however, most studies have focused on applying the microwave energy over a sizable area, which requires about ten times the energy that is embodied in conventional chemical treatments to achieve effective weed control. A closer analysis of the microwave heating phenomenon suggests that thermal runaway can reduce microwave weed treatment time by at least one order of magnitude. If thermal runaway can be induced in weed plants, the energy costs associated with microwave weed management would be comparable with chemical weed control.

  11. Few-photon optical diode

    CERN Document Server

    Roy, Dibyendu

    2010-01-01

    We propose a novel scheme of realizing an optical diode at the few-photon level. The system consists of a one-dimensional waveguide coupled asymmetrically to a two-level system. The two or multi-photon transport in this system is strongly correlated. We derive exactly the single and two-photon current and show that the two-photon current is asymmetric for the asymmetric coupling. Thus the system serves as an optical diode which allows transmission of photons in one direction much more efficiently than the opposite.

  12. Few-photon optical diode

    OpenAIRE

    Roy, Dibyendu

    2010-01-01

    We propose a novel scheme of realizing an optical diode at the few-photon level. The system consists of a one-dimensional waveguide coupled asymmetrically to a two-level system. The two or multi-photon transport in this system is strongly correlated. We derive exactly the single and two-photon current and show that the two-photon current is asymmetric for the asymmetric coupling. Thus the system serves as an optical diode which allows transmission of photons in one direction much more efficie...

  13. Few-photon optical diode

    OpenAIRE

    Roy, Dibyendu

    2010-01-01

    We propose a novel scheme of realizing an optical diode at the few-photon level. The system consists of a one-dimensional waveguide coupled asymmetrically to a two-level system. The two or multi-photon transport in this system is strongly correlated. We derive exactly the single and two-photon current and show that the two-photon current is asymmetric for the asymmetric coupling. Thus the system serves as an optical diode which allows transmission of photons in one direction much more efficie...

  14. Scaling of nano-Schottky-diodes

    NARCIS (Netherlands)

    Smit, G.D.J.; Rogge, S.; Klapwijk, T.M.

    2002-01-01

    A generally applicable model is presented to describe the potential barrier shape in ultrasmall Schottky diodes. It is shown that for diodes smaller than a characteristic length lc (associated with the semiconductor doping level) the conventional description no longer holds. For such small diodes th

  15. Manufacturing Practices for Silicon-Based Power Diode in Fast Recovery Applications

    Directory of Open Access Journals (Sweden)

    N. Harihara Krishnan

    2011-01-01

    Full Text Available This paper reports a fast recovery semiconductor diode that was developed for use in high power applications. The diode constructed in disc-type ceramic package with a peak-inverse voltage rating of 2800 V and current rating of 710 A was fabricated using float-zone (FZ silicon wafer as the starting raw material. Alternate processes viz. gold diffusion, gamma irradiation and electron irradiation were explored for control of carrier lifetime required to tune the switching response of the diode to the desired value of 8 μs. The paper compares the results of these alternate processes. The diodes were fabricated and tested for forward conduction, reverse blocking and switching characteristics. The measured values were observed to be comparable with the design requirements. The paper presents an overview of the design, manufacturing and testing practices adopted to meet the desired diode characteristics and ratings.

  16. A new diode laser acupuncture therapy apparatus

    Science.gov (United States)

    Li, Chengwei; Huang, Zhen; Li, Dongyu; Zhang, Xiaoyuan

    2006-06-01

    Since the first laser-needles acupuncture apparatus was introduced in therapy, this kind of apparatus has been well used in laser biomedicine as its non-invasive, pain- free, non-bacterium, and safetool. The laser acupuncture apparatus in this paper is based on single-chip microcomputer and associated by semiconductor laser technology. The function like traditional moxibustion including reinforcing and reducing is implemented by applying chaos method to control the duty cycle of moxibustion signal, and the traditional lifting and thrusting of acupuncture is implemented by changing power output of the diode laser. The radiator element of diode laser is made and the drive circuit is designed. And chaos mathematic model is used to produce deterministic class stochastic signal to avoid the body adaptability. This function covers the shortages of continuous irradiation or that of simple disciplinary stimulate signal, which is controlled by some simple electronic circuit and become easily adjusted by human body. The realization of reinforcing and reducing of moxibustion is technological innovation in traditional acupuncture coming true in engineering.

  17. Microwave assisted template synthesis of silver nanoparticles

    Indian Academy of Sciences (India)

    K J Sreeram; M Nidhin; B U Nair

    2008-12-01

    Easier, less time consuming, green processes, which yield silver nanoparticles of uniform size, shape and morphology are of interest. Various methods for synthesis, such as conventional temperature assisted process, controlled reaction at elevated temperatures, and microwave assisted process have been evaluated for the kind of silver nanoparticles synthesized. Starch has been employed as a template and reducing agent. Electron microscopy, photon correlation spectroscopy and surface plasmon resonance have been employed to characterize the silver nanoparticles synthesized. Compared to conventional methods, microwave assisted synthesis was faster and provided particles with an average particle size of 12 nm. Further, the starch functions as template, preventing the aggregation of silver nanoparticles.

  18. Characteristics of Cylindrical Microwave Plasma Source at Low Pressure

    Science.gov (United States)

    Park, Seungil; Youn, S.; Kim, S. B.; Yoo, S. J.

    2016-10-01

    A microwave plasma source with a cylindrical resonance cavity has been proposed to generate the plasma at low pressure. This plasma source consists of magnetron, waveguide, antenna, and cavity. The microwave generating device is a commercial magnetron with 1 kW output power at the frequency of 2.45 GHz. The microwave is transmitted through the rectangular waveguide with the whistle shape, and coupled to the cavity by the slot antenna. The resonant mode of the cylindrical cavity is the TE111 mode. The operating pressure is between 0.1 Torr and 0.3 Torr with the Argon and nitrogen gas. The electron temperature and electron number density of argon plasma were measured with the optical emission spectroscopy measurement. And Ar1s5 metastable density was measured using tunable diode laser absorption spectroscopy (TDLAS). The plasma diagnostic results of a cylindrical microwave plasma source would be described in this study. This work was supported by R&D Program of ``Plasma Advanced Technology for Agriculture and Food (Plasma Farming)'' through the National Fusion Research Institute of Korea (NFRI) funded by the Government funds.

  19. Progress of the technique of coal microwave desulfurization

    Institute of Scientific and Technical Information of China (English)

    Xiuxiang Tao; Ning Xu; Maohua Xie; Longfei Tang

    2014-01-01

    With the advantages of its fast speed, effective and moderate controllable conditions, desulfurization of coal by microwave has become research focus in the field of clean coal technology. Coal is a homogeneous mixture which consists of various components with different dielectric properties, so their abilities to absorb microwaves are different, and the sulfur-containing components are better absorbers of microwave, which makes them can be selectively heated and reacted under microwave irradiation. There still remain controversies on the principle of microwave desulfurization at present, thermal effects or non-thermal effects. The point of thermal effects of microwave is mainly base on its characters of rapidly and selectly heating. While, in view of non-thermal effect, direct interactions between the microwave electromagnetic field and sulfur containing components are proposed. It is a fundamental problem to determine the dielectric properties of coal and the sulfur-containing components to reveal the interaction of microwave and sulfur-containing compounds. However, the test of dielectric property of coal is affected by many factors, which makes it difficult to measure dielectric properties accurately. In order to achieve better desulfurization effect, the researchers employ methods of adding chemical additives such as acid, alkali, oxidant, reductant, or changing the reaction atmosphere, or combining with other methods such as magnetic separation, ultrasonic and microorganism. Researchers in this field have also put forward several processes, and have obtained a number of patents. Obscurity of microwave desulfurization mechanism, uncertainties in qualitative and quantitative analysis of sulfur-containing functional groups in coal, and the lack of special microwave equipment have limited further development of microwave desulfurization technology.

  20. Research on reverse recovery characteristics of SiGeC p-i-n diodes

    Institute of Scientific and Technical Information of China (English)

    Gao Yong; Liu Jing; Yang Yuan

    2008-01-01

    This paper analyses the reverse recovery characteristics and mechanism of SiGeC p-i-n diodes. Based on the integrated systems engineering (ISE) data, the critical physical models of SiGeC diodes are proposed. Based on heterojunction band gap engineering, the softness factor increases over six times, reverse recovery time is over 30% short and there is a 20% decrease in peak reverse recovery current for SiGeC diodes with 20% of germanium and 0.5% of carbon,compared to Si diodes. Those advantages of SiGeC p-i-n diodes are more obvious at high temperature. Compared to lifetime control, SiGeC technique is more suitable for improving diode properties and the tradeoff between reverse recovery time and forward voltage drop can be easily achieved in SiGeC diodes. Furthermore, the high thermal-stability of SiGeC diodes reduces the costs of further process steps and offers more freedoms to device design.

  1. Testing of Diode-Clamping in an Inductive Pulsed Plasma Thruster Circuit

    Science.gov (United States)

    Toftul, Alexandra; Polzin, Kurt A.; Martin, Adam K.; Hudgins, Jerry L.

    2014-01-01

    Testing of a 5.5 kV silicon (Si) diode and 5.8 kV prototype silicon carbide (SiC) diode in an inductive pulsed plasma thruster (IPPT) circuit was performed to obtain a comparison of the resulting circuit recapture efficiency,eta(sub r), defined as the percentage of the initial charge energy remaining on the capacitor bank after the diode interrupts the current. The diode was placed in a pulsed circuit in series with a silicon controlled rectifier (SCR) switch, and the voltages across different components and current waveforms were collected over a range of capacitor charge voltages. Reverse recovery parameters, including turn-off time and peak reverse recovery current, were measured and capacitor voltage waveforms were used to determine the recapture efficiency for each case. The Si fast recovery diode in the circuit was shown to yield a recapture efficiency of up to 20% for the conditions tested, while the SiC diode further increased recapture efficiency to nearly 30%. The data presented show that fast recovery diodes operate on a timescale that permits them to clamp the discharge quickly after the first half cycle, supporting the idea that diode-clamping in IPPT circuit reduces energy dissipation that occurs after the first half cycle

  2. Crossed-beam superluminescent diode.

    Science.gov (United States)

    Vaissié, Laurent; Smolski, Oleg V; Johnson, Eric G

    2005-07-01

    We investigate a novel surface-emitting superluminescent diode configuration that uses two detuned grating outcouplers to suppress lasing. This device exhibits a shaped beam with a peak power of 1.5 W quasi-continuous wave with an 11 nm bandwidth centered on 970 nm.

  3. Objective Characterization of Snow Microstructure for Microwave Emission Modeling

    Science.gov (United States)

    Durand, Michael; Kim, Edward J.; Molotch, Noah P.; Margulis, Steven A.; Courville, Zoe; Malzler, Christian

    2012-01-01

    Passive microwave (PM) measurements are sensitive to the presence and quantity of snow, a fact that has long been used to monitor snowcover from space. In order to estimate total snow water equivalent (SWE) within PM footprints (on the order of approx 100 sq km), it is prerequisite to understand snow microwave emission at the point scale and how microwave radiation integrates spatially; the former is the topic of this paper. Snow microstructure is one of the fundamental controls on the propagation of microwave radiation through snow. Our goal in this study is to evaluate the prospects for driving the Microwave Emission Model of Layered Snowpacks with objective measurements of snow specific surface area to reproduce measured brightness temperatures when forced with objective measurements of snow specific surface area (S). This eliminates the need to treat the grain size as a free-fit parameter.

  4. Loads due to stray microwave radiation in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Oosterbeek, Johan W. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Eindhoven University of Technology, P.O. Box 513, 5600 AZ Eindhoven (Netherlands); Udintsev, Victor S.; Gandini, Franco [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Hirsch, Matthias; Laqua, Heinrich P. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, D-17489 Greifswald (Germany); Maassen, Nick [Eindhoven University of Technology, P.O. Box 513, 5600 AZ Eindhoven (Netherlands); Ma, Yunxing; Polevoi, Alexei; Sirinelli, Antoine; Vayakis, George; Walsh, Mike J. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France)

    2015-10-15

    High-power microwaves generated by gyrotrons will be extensively used in ITER for a variety of purposes such as assisting plasma breakdown, plasma heating, current drive, tearing mode suppression and as a probing beam for the Collective Thomson Scattering diagnostic. In a number of these schemes absorption of the microwaves by the plasma will not be full and in some cases there could be no absorption at all. This may result in a directed beam with a high microwave power flux or – depending on location and plasma conditions – an approximately isotropic microwave power field. The contribution of electron cyclotron emission to these power densities is briefly discussed. Exposure to in-vessel components leads to absorption by metals and ceramics. In this paper microwave power densities are estimated and, following a brief review of absorption, thermal loads on in-vessel components are assessed. The paper is concluded by a discussion of the current approach to control such loads.

  5. Measurement of high-power microwave pulse under intense electromagnetic noise

    Indian Academy of Sciences (India)

    Amitava Roy; S K Singh; R Menon; D Senthil Kumar; R Venkateswaran; M R Kulkarni; P C Saroj; K V Nagesh; K C Mittal; D P Chakravarthy

    2010-01-01

    KALI-1000 pulse power system has been used to generate single pulse nanosecond duration high-power microwaves (HPM) from a virtual cathode oscillator (VIRCATOR) device. HPM power measurements were carried out using a transmitting–receiving system in the presence of intense high frequency (a few MHz) electromagnetic noise. Initially, the diode detector output signal could not be recorded due to the high noise level persisting in the ambiance. It was found that the HPM pulse can be successfully detected using wide band antenna, RF cable and diode detector set-up in the presence of significant electromagnetic noise. Estimated microwave peak power was ∼ 59.8 dBm (∼ 1 kW) at 7 m distance from the VIRCATOR window. Peak amplitude of the HPM signal varies on shot-to-shot basis. Duration of the HPM pulse (FWHM) also varies from 52 ns to 94 ns for different shots.

  6. Anomalous Microwave Emission

    CERN Document Server

    Kogut, A J

    1999-01-01

    Improved knowledge of diffuse Galactic emission is important to maximize the scientific return from scheduled CMB anisotropy missions. Cross-correlation of microwave maps with maps of the far-IR dust continuum show a ubiquitous microwave emission component whose spatial distribution is traced by far-IR dust emission. The spectral index of this emission, beta_{radio} = -2.2 (+0.5 -0.7) is suggestive of free-free emission but does not preclude other candidates. Comparison of H-alpha and microwave results show that both data sets have positive correlations with the far-IR dust emission. Microwave data, however, are consistently brighter than can be explained solely from free-free emission traced by H-alpha. This ``anomalous'' microwave emission can be explained as electric dipole radiation from small spinning dust grains. The anomalous component at 53 GHz is 2.5 times as bright as the free-free emission traced by H-alpha, providing an approximate normalization for models with significant spinning dust emission.

  7. Noninvasive Temperature Measurement Based on Microwave Temperature Sensor

    Directory of Open Access Journals (Sweden)

    Shoucheng Ding

    2013-01-01

    Full Text Available In this study, we have a research of the noninvasive temperature measurement based on microwave temperature sensor. Moreover, in order to solve the surface temperature measurement for designing microwave temperature sensor, the microwave was issued by the transmitting antenna. Microwave encountered by the measured object to return back to the measured object and then convert it into electrical signals, the use of the quantitative relationship between this signal and input noise temperature to real-time calibration. In order to calculate the antenna brightness temperature and then after signal conditioning circuit, which can show the temperature value, in order to achieve the detection of microwave temperature. Microwave-temperature measurement system hardware based on 89C51 microcontroller consists of the microwave temperature sensor, signal conditioning circuitry and chip control circuit, AD converter circuit and display circuit. The system software is by the main program, the AD conversion routines, subroutines and delay subprogram. The microwave temperature measurement characterize has: without gain fluctuations, without the impact of changes in the noise of the machine, to provide continuous calibration, wide dynamic range.

  8. Muscular pre-conditioning using light-emitting diode therapy (LEDT) for high-intensity exercise: a randomized double-blind placebo-controlled trial with a single elite runner.

    Science.gov (United States)

    Ferraresi, Cleber; Beltrame, Thomas; Fabrizzi, Fernando; do Nascimento, Eduardo Sanches Pereira; Karsten, Marlus; Francisco, Cristina de Oliveira; Borghi-Silva, Audrey; Catai, Aparecida Maria; Cardoso, Daniel Rodrigues; Ferreira, Antonio Gilberto; Hamblin, Michael R; Bagnato, Vanderlei Salvador; Parizotto, Nivaldo Antonio

    2015-07-01

    Recently, low-level laser (light) therapy (LLLT) has been used to improve muscle performance. This study aimed to evaluate the effectiveness of near-infrared light-emitting diode therapy (LEDT) and its mechanisms of action to improve muscle performance in an elite athlete. The kinetics of oxygen uptake (VO2), blood and urine markers of muscle damage (creatine kinase--CK and alanine), and fatigue (lactate) were analyzed. Additionally, some metabolic parameters were assessed in urine using proton nuclear magnetic resonance spectroscopy ((1)H NMR). A LED cluster with 50 LEDs (λ = 850 nm; 50 mW 15 s; 37.5 J) was applied on legs, arms and trunk muscles of a single runner athlete 5 min before a high-intense constant workload running exercise on treadmill. The athlete received either Placebo-1-LEDT; Placebo-2-LEDT; or Effective-LEDT in a randomized double-blind placebo-controlled trial with washout period of 7 d between each test. LEDT improved the speed of the muscular VO2 adaptation (∼-9 s), decreased O2 deficit (∼-10 L), increased the VO2 from the slow component phase (∼+348 ml min(-1)), and increased the time limit of exercise (∼+589 s). LEDT decreased blood and urine markers of muscle damage and fatigue (CK, alanine and lactate levels). The results suggest that a muscular pre-conditioning regimen using LEDT before intense exercises could modulate metabolic and renal function to achieve better performance.

  9. Locking IR and UV diode lasers to a visible laser using a LabVIEW PID controller on a Fabry-Perot signal

    CERN Document Server

    Kwolek, J M; Goodman, D S; Smith, W W

    2015-01-01

    Simultaneous laser locking of IR and UV lasers to a visible reference laser is demonstrated via a Fabry-Perot cavity. LabVIEW is used to analyze the input and an internal PID algorithm converts the Fabry-Perot signal to an analog locking feedback signal. The locking program stabilized both lasers to a long term stability of less than 12 MHz, with the lab-built IR laser undergoing signi?cant improvement in frequency stabilization. The results of this study demonstrate the viability of a simple computer-controlled, non temperature-stabilized Fabry-Perot locking scheme for our applications, laser cooling of Ca+ ions, and its use in other applications with similar modest frequency stabilization requirements.

  10. Simple locking of infrared and ultraviolet diode lasers to a visible laser using a LabVIEW proportional-integral-derivative controller on a Fabry-Perot signal.

    Science.gov (United States)

    Kwolek, J M; Wells, J E; Goodman, D S; Smith, W W

    2016-05-01

    Simultaneous laser locking of infrared (IR) and ultraviolet lasers to a visible stabilized reference laser is demonstrated via a Fabry-Perot (FP) cavity. LabVIEW is used to analyze the input, and an internal proportional-integral-derivative algorithm converts the FP signal to an analog locking feedback signal. The locking program stabilized both lasers to a long term stability of better than 9 MHz, with a custom-built IR laser undergoing significant improvement in frequency stabilization. The results of this study demonstrate the viability of a simple, computer-controlled, non-temperature-stabilized FP locking scheme for our applications, laser cooling of Ca(+) ions, and its use in other applications with similar modest frequency stabilization requirements.

  11. Simple locking of infrared and ultraviolet diode lasers to a visible laser using a LabVIEW proportional-integral-derivative controller on a Fabry-Perot signal

    Science.gov (United States)

    Kwolek, J. M.; Wells, J. E.; Goodman, D. S.; Smith, W. W.

    2016-05-01

    Simultaneous laser locking of infrared (IR) and ultraviolet lasers to a visible stabilized reference laser is demonstrated via a Fabry-Perot (FP) cavity. LabVIEW is used to analyze the input, and an internal proportional-integral-derivative algorithm converts the FP signal to an analog locking feedback signal. The locking program stabilized both lasers to a long term stability of better than 9 MHz, with a custom-built IR laser undergoing significant improvement in frequency stabilization. The results of this study demonstrate the viability of a simple, computer-controlled, non-temperature-stabilized FP locking scheme for our applications, laser cooling of Ca+ ions, and its use in other applications with similar modest frequency stabilization requirements.

  12. Controls on ERS altimeter measurements over ice sheets: Footprint-scale topography, backscatter fluctuations, and the dependence of microwave penetration depth on satellite orientation

    Science.gov (United States)

    Arthern, R. J.; Wingham, D. J.; Ridout, A. L.

    2001-12-01

    We consider the reliability of radar altimeter measurements of ice sheet elevation and snowpack properties in the presence of surface undulations. We demonstrate that over ice sheets the common practice of averaging echoes by aligning the first return from the surface at the origin can result in a redistribution of power to later times in the average echo, mimicking the effects of microwave penetration into the snowpack. Algorithms that assume the topography affects the radar echo shape in the same way that waves affect altimeter echoes over the ocean will therefore lead to biased estimates of elevation. This assumption will also cause errors in the retrieval of echoshape parameters intended to quantify the penetration of the microwave pulse into the snowpack. Using numerical simulations, we estimate the errors in retrievals of extinction coefficient, surface backscatter, and volume backscatter for various undulating topographies. In the flatter portions of the Antarctic plateau, useful estimates of these parameters may be recovered by averaging altimeter echoes recorded by the European Remote Sensing satellite (ERS-1). By numerical deconvolution of the average echoes we resolve the depths in the snowpack at which temporal changes and satellite travel-direction effects occur, both of which have the potential to corrupt measurements of ice sheet elevation change. The temporal changes are isolated in the surface-backscatter cross section, while directional effects are confined to the extinction coefficient and are stable from year to year. This allows the removal of the directional effect from measurement of ice-sheet elevation change.

  13. High power microwaves

    CERN Document Server

    Benford, James; Schamiloglu, Edl

    2016-01-01

    Following in the footsteps of its popular predecessors, High Power Microwaves, Third Edition continues to provide a wide-angle, integrated view of the field of high power microwaves (HPMs). This third edition includes significant updates in every chapter as well as a new chapter on beamless systems that covers nonlinear transmission lines. Written by an experimentalist, a theorist, and an applied theorist, respectively, the book offers complementary perspectives on different source types. The authors address: * How HPM relates historically and technically to the conventional microwave field * The possible applications for HPM and the key criteria that HPM devices have to meet in order to be applied * How high power sources work, including their performance capabilities and limitations * The broad fundamental issues to be addressed in the future for a wide variety of source types The book is accessible to several audiences. Researchers currently in the field can widen their understanding of HPM. Present or pot...

  14. Microwave-assisted Chemical Transformations

    Science.gov (United States)

    In recent years, there has been a considerable interest in developing sustainable chemistries utilizing green chemistry principles. Since the first published report in 1986 by Gedye and Giguere on microwave assisted synthesis in household microwave ovens, the use of microwaves as...

  15. Physics of the Microwave Oven

    Science.gov (United States)

    Vollmer, Michael

    2004-01-01

    This is the first of two articles about the physics of microwave ovens. This article deals with the generation of microwaves in the oven and includes the operation of the magnetrons, waveguides and standing waves in resonant cavities. It then considers the absorption of microwaves by foods, discussing the dielectric relaxation of water,…

  16. Physics of the Microwave Oven

    Science.gov (United States)

    Vollmer, Michael

    2004-01-01

    This is the first of two articles about the physics of microwave ovens. This article deals with the generation of microwaves in the oven and includes the operation of the magnetrons, waveguides and standing waves in resonant cavities. It then considers the absorption of microwaves by foods, discussing the dielectric relaxation of water,…

  17. Investigating a Hypothetical Semiconductor Laser Bar Using a Laser Diode Simulation/Emulation Tool Using Random Levels of Defects

    Directory of Open Access Journals (Sweden)

    C.K. Amuzuvi

    2014-02-01

    Full Text Available In this study, Barlase, a semiconductor laser diode emulation tool, is used to emulate the by-emitter degradation of high power semiconductor laser diodes. Barlase is a software that uses a LabView control interface. We have demonstrated how Barlase works using a hypothetical laser diode bar (multiple emitters to validate the usefulness of the tool. A scenario using the hypothetical bar was investigated to demonstrate Barlase as follows: random low-level of defects distributed across the bar. The results of the simulation show the successful implementation of Barlase in the by-emitter analysis of laser diodes.

  18. A microwave powered sensor assembly for microwave ovens

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention relates to a microwave powered sensor assembly for micro- wave ovens. The microwave powered sensor assembly comprises a microwave antenna for generating an RF antenna signal in response to microwave radiation at a predetermined excitation frequency. A dc power supply circuit...... of the microwave powered sensor assembly is operatively coupled to the RF antenna signal for extracting energy from the RF antenna signal and produce a power supply voltage. A sensor is connected to the power supply voltage and configured to measure a physical or chemical property of a food item under heating...

  19. Role of diode lasers in oro-facial pain management.

    Science.gov (United States)

    Javed, F; Kellesarian, S V; Romanos, G E

    2017-01-01

    With the increasing use of low level laser therapy (LLLT) in clinical dentistry, the aim of the present study was to assess the effectiveness of diode lasers in the management of orofacial pain. Indexed databases were searched without language and time restrictions up to and including July 2016 using different combinations of the following key words: oral, low level laser therapy, dental, pain, diode lasers, discomfort and analgesia. From the literature reviewed it is evident that LLLT is effective compared to traditional procedures in the management of oro-facial pain associated to soft tissue and hard tissue conditions such as premalignant lesions, gingival conditions and dental extractions. However, it remains to be determined which particular wavelength will produce the more favorable and predictable outcome in terms of pain reduction. It is highly recommended that further randomized control trials with well-defined control groups should be performed to determine the precise wavelengths of the diode lasers for the management of oro-facial pain. Within the limits of the present review, it is concluded that diode lasers therapy is more effective in the management of oro-facial pain compared to traditional procedures.

  20. Pseudoepitheliomatous hyperplasia after diode laser oral surgery. An experimental study

    Science.gov (United States)

    Seoane, Juan; González-Mosquera, Antonio; García-Martín, José-Manuel; García-Caballero, Lucía; Varela-Centelles, Pablo

    2015-01-01

    Background To examine the process of epithelial reparation in a surgical wound caused by diode laser. Material and Methods An experimental study with 27 Sprage-Dawley rats was undertaken. The animals were randomly allocated to two experimental groups, whose individuals underwent glossectomy by means of a diode laser at different wattages, and a control group treated using a number 15 scalpel blade. The animals were slaughtered at the 2nd, 7th, and 14th day after glossectomy. The specimens were independently studied by two pathologists (blinded for the specimens’ group). Results At the 7th day, re-epithelisation was slightly faster for the control group (conventional scalpel) (p=0.011). At the 14th day, complete re-epithelization was observed for all groups. The experimental groups displayed a pseudoepitheliomatous hyperplasia. Conclusions It is concluded that, considering the limitations of this kind of experimental studies, early re-epithelisation occurs slightly faster when a conventional scalpel is used for incision, although re-epithelisation is completed in two weeks no matter the instrument used. In addition, pseudoepitheliomatous hyperplasia is a potential event after oral mucosa surgery with diode laser. Knowledge about this phenomenon (not previously described) may prevent diagnostic mistakes and inadequate treatment approaches, particularly when dealing with potentially malignant oral lesions. Key words:Diode laser, animal model, oral biopsy, oral cancer, oral precancer, pseudoepitheliomatous hyperplasia. PMID:26116841

  1. Microwave Frequency Polarizers

    Science.gov (United States)

    Ha, Vien The; Mirel, Paul; Kogut, Alan J.

    2013-01-01

    This article describes the fabrication and analysis of microwave frequency polarizing grids. The grids are designed to measure polarization from the cosmic microwave background. It is effective in the range of 500 to 1500 micron wavelength. It is cryogenic compatible and highly robust to high load impacts. Each grid is fabricated using an array of different assembly processes which vary in the types of tension mechanisms to the shape and size of the grids. We provide a comprehensive study on the analysis of the grids' wire heights, diameters, and spacing.

  2. Microwave Discharge Ion Sources

    CERN Document Server

    Celona, L

    2013-01-01

    This chapter describes the basic principles, design features and characteristics of microwave discharge ion sources. A suitable source for the production of intense beams for high-power accelerators must satisfy the requirements of high brightness, stability and reliability. The 2.45 GHz off-resonance microwave discharge sources are ideal devices to generate the required beams, as they produce multimilliampere beams of protons, deuterons and singly charged ions. A description of different technical designs will be given, analysing their performance, with particular attention being paid to the quality of the beam, especially in terms of its emittance.

  3. Fundamentals of microwave photonics

    CERN Document Server

    Urick, V J; McKinney , Jason D

    2015-01-01

    A comprehensive resource to designing andconstructing analog photonic links capable of high RFperformanceFundamentals of Microwave Photonics provides acomprehensive description of analog optical links from basicprinciples to applications.  The book is organized into fourparts. The first begins with a historical perspective of microwavephotonics, listing the advantages of fiber optic links anddelineating analog vs. digital links. The second section coversbasic principles associated with microwave photonics in both the RFand optical domains.  The third focuses on analog modulationformats-starti

  4. Microwave circulator design

    CERN Document Server

    Linkhart, Douglas K

    2014-01-01

    Circulator design has advanced significantly since the first edition of this book was published 25 years ago. The objective of this second edition is to present theory, information, and design procedures that will enable microwave engineers and technicians to design and build circulators successfully. This resource contains a discussion of the various units used in the circulator design computations, as well as covers the theory of operation. This book presents numerous applications, giving microwave engineers new ideas about how to solve problems using circulators. Design examples are provided, which demonstrate how to apply the information to real-world design tasks.

  5. EDITORIAL: Microwave Moisture Measurements

    Science.gov (United States)

    Kaatze, Udo; Kupfer, Klaus; Hübner, Christof

    2007-04-01

    Microwave moisture measurements refer to a methodology by which the water content of materials is non-invasively determined using electromagnetic fields of radio and microwave frequencies. Being the omnipresent liquid on our planet, water occurs as a component in most materials and often exercises a significant influence on their properties. Precise measurements of the water content are thus extremely useful in pure sciences, particularly in biochemistry and biophysics. They are likewise important in many agricultural, technical and industrial fields. Applications are broad and diverse, and include the quality assessment of foodstuffs, the determination of water content in paper, cardboard and textile production, the monitoring of moisture in sands, gravels, soils and constructions, as well as the measurement of water admixtures to coal and crude oil in reservoirs and in pipelines. Microwave moisture measurements and evaluations require insights in various disciplines, such as materials science, dielectrics, the physical chemistry of water, electrodynamics and microwave techniques. The cooperation of experts from the different fields of science is thus necessary for the efficient development of this complex discipline. In order to advance cooperation the Workshop on Electromagnetic Wave Interaction with Water and Moist Substances was held in 1993 in Atlanta. It initiated a series of international conferences, of which the last one was held in 2005 in Weimar. The meeting brought together 130 scientists and engineers from all over the world. This special issue presents a collection of some selected papers that were given at the event. The papers cover most topics of the conference, featuring dielectric properties of aqueous materials, electromagnetic wave interactions, measurement methods and sensors, and various applications. The special issue is dedicated to Dr Andrzej W Kraszewski, who died in July 2006 after a distinguished career of 48 years in the research of

  6. Fabrication and Characterization of n-AlGaAs/GaAs Schottky Diode for Rectenna Device Application

    Science.gov (United States)

    Parimon, Norfarariyanti; Mustafa, Farahiyah; Manaf Hashim, Abdul; Fadzli Abd Rahman, Shaharin; Rahman, Abdul Rahim Abdul; Nizam Osman, Mohd

    2011-02-01

    Schottky diode was designed and fabricated on n-AlGaAs/GaAs high electron mobility transistor (HEMT) structure for rectenna device application. Rectenna is one of the most potential devices to form the wireless power supply which is really good at converting microwaves to DC. The processing steps used in the fabrication of Schottky diode were the conventional steps used in standard GaAs processing. Current-voltage (I-V) measurements showed that the device had rectifying properties with a barrier height of 0.5468 eV for Ni/Au metallization. The fabricated Schottky diode detected RF signals and the cut-off frequency up to 20 GHz was estimated in direct injection experiments. These preliminary results will provide a breakthrough for the direct integration with antenna towards realization of rectenna device application.

  7. Fabrication and Characterization of n-AlGaAs/GaAs Schottky Diode for Rectenna Device Application

    Energy Technology Data Exchange (ETDEWEB)

    Parimon, Norfarariyanti; Mustafa, Farahiyah; Hashim, Abdul Manaf; Rahman, Shaharin Fadzli Abd; Rahman, Abdul Rahim Abdul [Material Innovations and Nanoelectronics Research Group, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Osman, Mohd Nizam, E-mail: manaf@fke.utm.my [Telekom Research and Development, TM Innovation Centre, 63000 Cyberjaya (Malaysia)

    2011-02-15

    Schottky diode was designed and fabricated on n-AlGaAs/GaAs high electron mobility transistor (HEMT) structure for rectenna device application. Rectenna is one of the most potential devices to form the wireless power supply which is really good at converting microwaves to DC. The processing steps used in the fabrication of Schottky diode were the conventional steps used in standard GaAs processing. Current-voltage (I-V) measurements showed that the device had rectifying properties with a barrier height of 0.5468 eV for Ni/Au metallization. The fabricated Schottky diode detected RF signals and the cut-off frequency up to 20 GHz was estimated in direct injection experiments. These preliminary results will provide a breakthrough for the direct integration with antenna towards realization of rectenna device application.

  8. Chlorine Analysis by Diode Laser Atomic Absorption Spectrometry

    Institute of Scientific and Technical Information of China (English)

    Joachim Koch; Aleksandr Zybin; Kay Niemax

    2000-01-01

    The general characteristics of Diode Laser Absorption Spectrometry (DLAAS) in low pressure plasmas particulary with respect to the detection of non-metals are comprehensively recapitulated and discussed. Furthermore, a detector, which is based on DLAAS in a microwave-induced low pressure plasma as an alternative technique for halogene-specific analysis of volatile compounds and polymeric matrices is described. The analytical capability of the technique is demonstrated on the chlorine-specific analysis of ablated polymer fragments as well as gas chromatographically separated hydrocarbons. Since the measurements were carried out by means of a balanced-heterodyne detection scheme, different technical noise contributions, such as laser excess and RAM noise could efficiently be suppressed and the registered absorption was limited only by the principal shot noise. Thus, in the case of the polymer analysis a chlorine-specific absolute detection limit of 10 pg could be achieved. Furthermore, fundamental investigations concerning the influence of hydrocarbons on the dissociation capability of the microwave induced plasma were performed. For this purpose, the carbon-, chlorine-and hydrogen-specific stoichiometry of the compounds were empirically determined. Deviations from the exspected proportions were found to be insignificant, implying the possibility of internal standardization relative to the response of a reference sample.

  9. Controlled synthesis and magnetic properties of monodisperse Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}/MWCNT nanocomposites via microwave-assisted polyol process

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Huaqiang, E-mail: wuhuaq@mail.ahnu.edu.cn [College of Chemistry and Materials Science, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, Wuhu 241000 (China); Zhang, Ning; Mao, Li; Li, Tingting; Xia, Lingling [College of Chemistry and Materials Science, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, Wuhu 241000 (China)

    2013-03-25

    Highlights: ► Microwave-assisted polyol preparation of monodisperse Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}/MWCNT nanocomposites. ► The composition can be controlled through adjusting the atomic ratios of nickel and zinc salts. ► Ms reaches maximum for x = 0.5. Hc is low and thus exhibits superparamagnetic. -- Abstract: Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}/MWCNT nanocomposites (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1) with controllable composition have been successfully synthesized via microwave-assisted polyol process using triethylene glycol solution (TREG) as solvent. Experimental results demonstrated that monodisperse face-centered cubical Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} nanoparticles with average size (6 nm) had been attached on the MWCNTs. The composition of ferrite nanoparticles can be controlled through adjusting the atomic ratios of the nickel and zinc salts in the mixed nitrate solution. The magnetic properties of nanocomposites with different Zn contents were measured by vibrating sample magnetometer (VSM). The saturation magnetization (Ms) of Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}/MWCNT nanocomposites gradually increases when the x is less than 0.5 while decreases when the x is larger than 0.5. Ms reached maximum value when the x is 0.5. The coercivity (Hc) of nanocomposites is low at room temperature, which exhibits characteristic of superparamagnetic.

  10. Design of drive circuit of laser diode

    Science.gov (United States)

    Ran, Yingying; Huang, Xuegong; Xu, Xiaobin

    2016-10-01

    Aiming at the difficult problem of high precision frequency stabilization of semiconductor laser diode, the laser frequency control is realized through the design of the semiconductor drive system. Above all, the relationship between the emission frequency and the temperature of LD is derived theoretically. Then the temperature corresponding to the stable frequency is obtained. According to the desired temperature stability of LD, temperature control system is designed, which is composed of a temperature setting circuit, temperature gathering circuit, the temperature display circuit, analog PID control circuit and a semiconductor refrigerator control circuit module. By sampling technology, voltage of platinum resistance is acquired, and the converted temperature is display on liquid crystal display. PID analog control circuit controls speed stability and precision of temperature control. The constant current source circuit is designed to provide the reference voltage by a voltage stabilizing chip, which is buffered by an operational amplifier. It is connected with the MOSFET to drive the semiconductor laser to provide stable current for the semiconductor laser. PCB circuit board was finished and the experimental was justified. The experimental results show that: the design of the temperature control system could achieve the goal of temperature monitoring. Meanwhile, temperature can be stabilized at 40°C +/- 0.1°C. The output voltage of the constant current source is 2 V. The current is 35 mA.

  11. Rapid detection of Ganoderma-infected oil palms by microwave ergosterol extraction with HPLC and TLC.

    Science.gov (United States)

    Muniroh, M S; Sariah, M; Zainal Abidin, M A; Lima, N; Paterson, R R M

    2014-05-01

    Detection of basal stem rot (BSR) by Ganoderma of oil palms was based on foliar symptoms and production of basidiomata. Enzyme-Linked Immunosorbent Assays-Polyclonal Antibody (ELISA-PAB) and PCR have been proposed as early detection methods for the disease. These techniques are complex, time consuming and have accuracy limitations. An ergosterol method was developed which correlated well with the degree of infection in oil palms, including samples growing in plantations. However, the method was capable of being optimised. This current study was designed to develop a simpler, more rapid and efficient ergosterol method with utility in the field that involved the use of microwave extraction. The optimised procedure involved extracting a small amount of Ganoderma, or Ganoderma-infected oil palm suspended in low volumes of solvent followed by irradiation in a conventional microwave oven at 70°C and medium high power for 30s, resulting in simultaneous extraction and saponification. Ergosterol was detected by thin layer chromatography (TLC) and quantified using high performance liquid chromatography with diode array detection. The TLC method was novel and provided a simple, inexpensive method with utility in the field. The new method was particularly effective at extracting high yields of ergosterol from infected oil palm and enables rapid analysis of field samples on site, allowing infected oil palms to be treated or culled very rapidly. Some limitations of the method are discussed herein. The procedures lend themselves to controlling the disease more effectively and allowing more effective use of land currently employed to grow oil palms, thereby reducing pressure to develop new plantations. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Quasi-passive heat sink for high-power laser diodes

    Science.gov (United States)

    Vetrovec, John

    2009-02-01

    We report on a novel heat sink for high-power laser diodes offering unparalleled capacity in high-heat flux handling and temperature control. The heat sink uses a liquid coolant flowing at high speed in a miniature closed and sealed loop. Diode waste heat is received at high flux and transferred to environment, coolant fluid, heat pipe, or structure at a reduced flux. When pumping solid-state or alkali vapor lasers, diode wavelength can be electronically tuned to the absorption features of the laser gain medium. This paper presents the heat sink physics, engineering design, performance modeling, and configurations.

  13. Microwave Radiation Hazards

    Directory of Open Access Journals (Sweden)

    G. Subrahmanian

    1973-07-01

    Full Text Available Excessive exposure to microwave radiation could lead to biological damage. The criteria for maximum permissible exposure limits derived from experiments by several countries are discussed. Recommendations made for safety of operating personnel based on a recent protection survey are also presented.

  14. Leakage of Microwave Ovens

    Science.gov (United States)

    Abdul-Razzaq, W.; Bushey, R.; Winn, G.

    2011-01-01

    Physics is essential for students who want to succeed in science and engineering. Excitement and interest in the content matter contribute to enhancing this success. We have developed a laboratory experiment that takes advantage of microwave ovens to demonstrate important physical concepts and increase interest in physics. This experiment…

  15. Leakage of Microwave Ovens

    Science.gov (United States)

    Abdul-Razzaq, W.; Bushey, R.; Winn, G.

    2011-01-01

    Physics is essential for students who want to succeed in science and engineering. Excitement and interest in the content matter contribute to enhancing this success. We have developed a laboratory experiment that takes advantage of microwave ovens to demonstrate important physical concepts and increase interest in physics. This experiment…

  16. Invisible to Microwaves

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Scientists can't yet make an invisibility cloak like the one that Harry Potter uses.But,for the first time,they've constructed a simple cloaking(1)d__that makes itself and something placed inside it invisible to microwaves.

  17. ORGANIC LIGHT EMITTING DIODE (OLED

    Directory of Open Access Journals (Sweden)

    Aririguzo Marvis Ijeaku

    2015-09-01

    Full Text Available An Organic Light Emitting Diode (OLED is a device composed of an organic layer that emits lights in response to an electrical current. Organic light emitting diodes have advanced tremendously over the past decades. The different manufacturing processes of the OLED itself to several advantages over flat panel displays made with LCD technology which includes its light weight and flexible plastic substrates, wider viewing angles, improved brightness, better power efficiency and quicker response time. However, its drawbacks include shorter life span, poor color balance, poor outdoor performance, susceptibility to water damage etc.The application of OLEDs in electronics is on the increase on daily basics from cameras to cell phones to OLED televisions, etc. Although OLEDs provides prospects for thinner, smarter, lighter and ultraflexible electronics displays, however, due to high cost of manufacturing, it is not yet widely used.

  18. Quantum Noise in Laser Diodes

    Science.gov (United States)

    Giacobino, E.; Marin, F.; Bramati, A.; Jost, V.; Poizat, J. Ph.; Roch, J.-F.; Grangier, P.; Zhang, T.-C.

    1996-01-01

    We have investigated the intensity noise of single mode laser diodes, either free-running or using different types of line narrowing techniques at room temperature. We have measured an intensity squeezing of 1.2 dB with grating-extended cavity lasers and 1.4 dB with injection locked lasers (respectively 1.6 dB and 2.3 dB inferred at the laser output). We have observed that the intensity noise of a free-running nominally single mode laser diode results from a cancellation effect between large anti-correlated fluctuations of the main mode and of weak longitudinal side modes. Reducing the side modes by line narrowing techniques results in intensity squeezing.

  19. Megahertz organic/polymer diodes

    Science.gov (United States)

    Katz, Howard Edan; Sun, Jia; Pal, Nath Bhola

    2012-12-11

    Featured is an organic/polymer diode having a first layer composed essentially of one of an organic semiconductor material or a polymeric semiconductor material and a second layer formed on the first layer and being electrically coupled to the first layer such that current flows through the layers in one direction when a voltage is applied in one direction. The second layer is essentially composed of a material whose characteristics and properties are such that when formed on the first layer, the diode is capable of high frequency rectifications on the order of megahertz rectifications such as for example rectifications at one of above 100KHz, 500KhZ, IMHz, or 10 MHz. In further embodiments, the layers are arranged so as to be exposed to atmosphere.

  20. Radiation-hardened microwave system

    Energy Technology Data Exchange (ETDEWEB)

    Smith, S.F.; Bible, D.W.; Crutcher, R.I.; Moore, J.A.; Nowlin, C.H.; Vandermolen, R.I.

    1990-01-01

    In order to develop a wireless communication system to meet the stringent requirements for a nuclear hot cell and similar environments, including control of advanced servomanipulators, a microwave signal transmission system development program was established to produce a demonstration prototype for the Consolidated Fuel Reprocessing Program at the Oak Ridge National Laboratory. Proof-of-principle tests in a partially metal lined enclosure at ORNL successfully demonstrated the feasibility of directed microwave signal transmission techniques for remote systems applications. The potential for much more severe RF multipath propagation conditions in fully metal lined cells led to a programmatic decision to conduct additional testing in more typical hot-cell environments at other sites. Again, the test results were excellent. Based on the designs of the earlier systems, an advanced MSTS configuration was subsequently developed that, in highly reflective environments, will support both high-performance video channels and high band-rate digital data links at total gamma dose tolerance levels exceeding 10{sup 7} rads and at elevated ambient temperatures. 3 refs., 4 figs.

  1. Characterisation of Silicon Pad Diodes

    CERN Document Server

    Hodson, Thomas Connor

    2017-01-01

    Silicon pad sensors are used in high luminosity particle detectors because of their excellent timing resolution, radiation tolerance and possible high granularity. The effect of different design decisions on detector performance can be investigated nondestructively through electronic characterisation of the sensor diodes. Methods for making accurate measurements of leakage current and cell capacitance are described using both a standard approach with tungsten needles and an automated approach with a custom multiplexer and probing setup.

  2. Tunneling spectroscopy of a p-i-n diode interface

    Energy Technology Data Exchange (ETDEWEB)

    Loth, Sebastian; Wenderoth, Martin; Teichmann, Karen; Homoth, Jan; Loeser, Karolin; Ulbrich, Rainer G. [IV. Physikalisches Institut, Georg-August-Universitaet Goettingen (Germany); Malzer, Stefan; Doehler, Gottfried H. [Universitaet Erlangen-Nuernberg (Germany). Max-Planck-Research Group, Institute of Optics, Information, and Photonics

    2008-07-01

    The performance of modern semiconductor devices is largely influenced by the spatial distribution of dopants in the device's active region on the nanoscale. Since the late 80's Scanning Tunneling Microscopy (STM) was employed to study the local properties of p-n interfaces. Most studies were carried out on p-n superlattices allowing the investigation of intrinsic features accessible without applied bias across the diode. Here, a single GaAs p-i-n diode heterostructure is investigated with cross-sectional STM (X-STM) in a three-terminal configuration. External source and drain contacts control the electric field across the junction. Then, the diode's active region is mapped with atomic resolution. Local I(V)-spectroscopy (STS) directly resolves the band edge alignment from p to n for different diode bias conditions. The effect of the external electric field on the spatial and spectral images of individual dopant atoms in the active layer is discussed.

  3. High power coherent polarization locked laser diode.

    Science.gov (United States)

    Purnawirman; Phua, P B

    2011-03-14

    We have coherently combined a broad area laser diode array to obtain high power single-lobed output by using coherent polarization locking. The single-lobed coherent beam is achieved by spatially combining four diode emitters using walk-off crystals and waveplates while their phases are passively locked via polarization discrimination. While our previous work focused on coherent polarization locking of diode in Gaussian beams, we demonstrate in this paper, the feasibility of the same polarization discrimination for locking multimode beams from broad area diode lasers. The resonator is designed to mitigate the loss from smile effect by using retro-reflection feedback in the cavity. In a 980 nm diode array, we produced 7.2 W coherent output with M2 of 1.5x11.5. The brightness of the diode is improved by more than an order of magnitude.

  4. Factors influencing the microwave pulse duration in a klystron-like relativistic backward wave oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Renzhen; Zhang Xiaowei; Zhang Ligang; Li Xiaoze; Zhang Lijun [National Key Laboratory of Science and Technology on High Power Microwave, Northwest Institute of Nuclear Technology, Xi' an 710024 (China)

    2012-07-15

    In this paper, we analyze the factors that affect the microwave pulse duration in a klystron-like relativistic backward wave oscillator (RBWO), including the diode voltage, the guiding magnetic field, the electron beam collector, the extraction cavity, and the gap between the electron beam and the slow wave structure (SWS). The results show that the microwave pulse duration increases with the diode voltage until breakdown occurs on the surface of the extraction cavity. The pulse duration at low guiding magnetic field is generally 5-10 ns smaller than that at high magnetic field due to the asymmetric electron emission and the larger energy spread of the electron beam. The electron beam collector can affect the microwave pulse duration significantly because of the anode plasma generated by bombardment of the electron beam on the collector surface. The introduction of the extraction cavity only slightly changes the pulse duration. The decrease of the gap between the electron beam and the SWS can increase the microwave pulse duration greatly.

  5. Common voltage eliminating of SVM diode clamping three-level inverter connected to grid

    DEFF Research Database (Denmark)

    Guo, Yougui; Zeng, Ping; Zhu, Jieqiong

    2011-01-01

    A novel method of common voltage eliminating is put forward for SVM diode clamping three-level inverter connected to grid by calculation of common voltage of its various switching states. PLECS is used to model this three-level inverter connected to grid and good results are obtained. First...... analysis of common mode voltage for switching states of diode clamping 3-level inverter is given in detail. Second the common mode voltage eliminating control strategy of SVM is described for diode clamping three-level inverter. Third, PLECS is briefly introduced. Fourth, the modeling of diode clamping...... three-level inverter is presented with PLECS. Finally, a series of simulations are carried out. The simulation results tell us PLECS is a very powerful tool to real power circuits modeling. They have also verified that proposed common mode voltage eliminating control strategy of SVM is feasible...

  6. Active coherent beam combining of diode lasers.

    Science.gov (United States)

    Redmond, Shawn M; Creedon, Kevin J; Kansky, Jan E; Augst, Steven J; Missaggia, Leo J; Connors, Michael K; Huang, Robin K; Chann, Bien; Fan, Tso Yee; Turner, George W; Sanchez-Rubio, Antonio

    2011-03-15

    We have demonstrated active coherent beam combination (CBC) of up to 218 semiconductor amplifiers with 38.5 W cw output using up to eleven one-dimensional 21-element individually addressable diode amplifier arrays operating at 960 nm. The amplifier array elements are slab-coupled-optical-waveguide semiconductor amplifiers (SCOWAs) set up in a master-oscillator-power-amplifier configuration. Diffractive optical elements divide the master-oscillator beam to seed multiple arrays of SCOWAs. A SCOWA was phase actuated by adjusting the drive current to each element and controlled using a stochastic-parallel-gradient-descent (SPGD) algorithm for the active CBC. The SPGD is a hill-climbing algorithm that maximizes on-axis intensity in the far field, providing phase locking without needing a reference beam.

  7. Practical application of a bidirectional microwave photonic filter: simultaneous transmission of analog TV signals

    Science.gov (United States)

    Correa-Mena, Ana Gabriela; Zaldívar-Huerta, Ignacio E.; Abril García, Jose Humberto; García-Juárez, Alejandro; Vera-Marquina, Alicia

    2016-10-01

    A practical application of a bidirectional microwave photonic filter (MPF) to transmit simultaneous analog TV signals coded on microwave carriers is experimentally demonstrated. The frequency response of the bidirectional MPF is obtained by the interaction of an externally modulated multimode laser diode emitting at 1.55 μm associated to the free-spectral range of the optical source, the chromatic dispersion parameter of the optical fiber, as well as the length of the optical link. The filtered microwave bandpass window generated around 2 GHz is used as electrical carrier in order to simultaneously transmit TV signals of 67.25 and 61.25 MHz in both directions. The obtained signal-to-noise ratios for the transmitted signals of 67.25 and 61.25 MHz are 37.62 and 44.77 dB, respectively.

  8. Compact high brightness diode laser emitting 500W from a 100μm fiber

    Science.gov (United States)

    Heinemann, Stefan; Fritsche, Haro; Kruschke, Bastian; Schmidt, Torsten; Gries, Wolfgang

    2013-02-01

    High power, high brightness diode lasers are beginning to compete with solid state lasers, i.e. disk and fiber lasers. The core technologies for brightness scaling of diode lasers are optical stacking and dense spectral combining (DSC), as well as improvements of the diode material. Diode lasers have the lowest cost of ownership, highest efficiency and most compact design among all lasers. Multiple Single Emitter (MSE) modules allow highest power and highest brightness diode lasers based on standard broad area diodes. Multiple single emitters, each rated at 12 W, are stacked in the fast axis with a monolithic slow axis collimator (SAC) array. Volume Bragg Gratings (VBG) stabilizes the wavelength and narrow the linewidth to less than 1 nm. Dichroic mirrors are used for dense wavelength multiplexing of 4 channels within 12 nm. Subsequently polarization multiplexing generates 450 W with a beam quality of 4.5 mm*mrad. Fast control electronics and miniaturized switched power supplies enable pulse rise times of less than 10 μs, with pulse widths continuously adjustable from 20 μs to cw. Further power scaling up to multi-kilowatts can be achieved by multiplexing up to 16 channels. The power and brightness of these systems enables the use of direct diode lasers for cutting and welding. The technologies can be transferred to other wavelengths to include 793 nm and 1530 nm. Optimized spectral combining enables further improvements in spectral brightness and power.

  9. Diode Laser Spectrum of the ν 1 Fundamental Band of PNO

    Science.gov (United States)

    Liu, Yuyan; Hamilton, P. A.; Davies, P. B.

    2002-01-01

    The diode laser spectrum of the ν1 fundamental band of the short-lived molecule PNO has been detected with 59 R- and P-branch lines accurately measured. The lines were unambiguously assigned using the rotational and distortion constants for the ground and (100) vibrational levels found previously by microwave spectroscopy. The band origin was determined to be 860.301 228(31) cm-1 from a one parameter fit. The gas phase band origin is red-shifted by approximately 4 cm-1 from the matrix value.

  10. Low temperature regeneration of activated carbons using microwaves: revising conventional wisdom.

    Science.gov (United States)

    Calışkan, E; Bermúdez, J M; Parra, J B; Menéndez, J A; Mahramanlıoğlu, M; Ania, C O

    2012-07-15

    The purpose of this work was to explore the application of microwaves for the low temperature regeneration of activated carbons saturated with a pharmaceutical compound (promethazine). Contrary to expectations, microwave-assisted regeneration did not lead to better results than those obtained under conventional electric heating. At low temperatures the regeneration was incomplete either under microwave and conventional heating, being this attributed to the insufficient input energy. At mild temperatures, a fall in the adsorption capacity upon cycling was obtained in both devices, although this was much more pronounced for the microwave. These results contrast with previous studies on the benefits of microwaves for the regeneration of carbon materials. The fall in the adsorption capacity after regeneration was due to the thermal cracking of the adsorbed molecules inside the carbon porous network, although this effect applies to both devices. When microwaves are used, along with the thermal heating of the carbon bed, a fraction of the microwave energy seemed to be directly used in the decomposition of promethazine through the excitation of the molecular bonds by microwaves (microwave-lysis). These results point out that the nature of the adsorbate and its ability to interact with microwave are key factors that control the application of microwaves for regeneration of exhausted activated carbons.

  11. Physics and Applications of Laser Diode Chaos

    CERN Document Server

    Sciamanna, Marc

    2015-01-01

    An overview of chaos in laser diodes is provided which surveys experimental achievements in the area and explains the theory behind the phenomenon. The fundamental physics underpinning this behaviour and also the opportunities for harnessing laser diode chaos for potential applications are discussed. The availability and ease of operation of laser diodes, in a wide range of configurations, make them a convenient test-bed for exploring basic aspects of nonlinear and chaotic dynamics. It also makes them attractive for practical tasks, such as chaos-based secure communications and random number generation. Avenues for future research and development of chaotic laser diodes are also identified.

  12. Effects of radiation on laser diodes.

    Energy Technology Data Exchange (ETDEWEB)

    Phifer, Carol Celeste

    2004-09-01

    The effects of ionizing and neutron radiation on the characteristics and performance of laser diodes are reviewed, and the formation mechanisms for nonradiative recombination centers, the primary type of radiation damage in laser diodes, are discussed. Additional topics include the detrimental effects of aluminum in the active (lasing) volume, the transient effects of high-dose-rate pulses of ionizing radiation, and a summary of ways to improve the radiation hardness of laser diodes. Radiation effects on laser diodes emitting in the wavelength region around 808 nm are emphasized.

  13. Advances in high power semiconductor diode lasers

    Science.gov (United States)

    Ma, Xiaoyu; Zhong, Li

    2008-03-01

    High power semiconductor lasers have broad applications in the fields of military and industry. Recent advances in high power semiconductor lasers are reviewed mainly in two aspects: improvements of diode lasers performance and optimization of packaging architectures of diode laser bars. Factors which determine the performance of diode lasers, such as power conversion efficiency, temperature of operation, reliability, wavelength stabilization etc., result from a combination of new semiconductor materials, new diode structures, careful material processing of bars. The latest progress of today's high-power diode lasers at home and abroad is briefly discussed and typical data are presented. The packaging process is of decisive importance for the applicability of high-power diode laser bars, not only technically but also economically. The packaging techniques include the material choosing and the structure optimizing of heat-sinks, the bonding between the array and the heat-sink, the cooling and the fiber coupling, etc. The status of packaging techniques is stressed. There are basically three different diode package architectural options according to the integration grade. Since the package design is dominated by the cooling aspect, different effective cooling techniques are promoted by different package architectures and specific demands. The benefit and utility of each package are strongly dependent upon the fundamental optoelectronic properties of the individual diode laser bars. Factors which influence these properties are outlined and comparisons of packaging approaches for these materials are made. Modularity of package for special application requirements is an important developing tendency for high power diode lasers.

  14. A randomized, placebo-controlled, single-blinded, split-faced clinical trial evaluating the efficacy and safety of KLOX-001 gel formulation with KLOX light-emitting diode light on facial rejuvenation

    Directory of Open Access Journals (Sweden)

    Nikolis A

    2016-05-01

    Full Text Available Andreas Nikolis,1 Steven Bernstein,2 Brian Kinney,3 Nicolo Scuderi,4 Shipra Rastogi,5 John S Sampalis6 1Victoria Park, Plastic Surgery Section, Westmount, QC, Canada; 2Dermatology Department, University of Montreal Health Centre, Montreal, QC, Canada; 3Department of Plastic Surgery, USC School of Medicine, Beverley Hills, CA, USA; 4Department of Plastic and Reconstructive Surgery, La Sapienza, Rome, Italy; 5KLOX Technologies, Laval, 6JSS Medical Research, Montreal, QC, Canada Purpose: Many treatment modalities exist to counteract the effects of cutaneous aging. Ablative methods have been the mainstay for nonsurgical facial rejuvenation. In recent years, nonablative techniques have been developed with the aim of achieving facial rejuvenation without epidermal damage. Light-emitting diode (LED photorejuvenation is a novel nonablative technique that induces collagen synthesis through biophotomodulatory pathways. Materials and methods: A single-center, randomized, single-blinded, placebo-controlled, split-faced clinical trial was designed. Thirty-two patients were enrolled for a 12-week study. Patients were randomized into one of four groups: Group A, treatment with KLOX-001 gel formulation and white LED (placebo light; Group B, treatment with a placebo/base gel (no active chromophore formulation and KLOX LED light; Group C, treatment with KLOX-001 gel formulation and KLOX LED light; and Group D, treatment with the standard skin rejuvenating treatment (0.1% retinol-based cream. Patients received treatment at weeks 0, 1, 2, and 3, and returned to the clinic at weeks 4, 8, and 12 for clinical assessments performed by an independent, blinded committee of physicians using subjective clinician assessment scales. Tolerability, adverse outcomes, and patient satisfaction were also assessed. Results: Analysis demonstrated that the KLOX LED light with KLOX placebo/base gel and the KLOX LED light + KLOX-001 gel formulation groups were superior to standard of

  15. Gigahertz dual-comb modelocked diode-pumped semiconductor and solid-state lasers

    Science.gov (United States)

    Link, S. M.; Mangold, M.; Golling, M.; Klenner, A.; Keller, U.

    2016-03-01

    We present a simple approach to generate simultaneously two gigahertz mode-locked pulse trains from a single gain element. A bi-refringent crystal in the laser cavity splits the one cavity beam into two cross-polarized and spatially separated beams. This polarization-duplexing is successfully demonstrated for both a semiconductor disk laser (i.e. MIXSEL) and a diode-pumped solid-state Nd:YAG laser. The beat between the two beams results in a microwave frequency comb, which represents a direct link between the terahertz optical frequencies and the electronically accessible microwave regime. This dual-output technique enables compact and cost-efficient dual-comb lasers for spectroscopy applications.

  16. Piezoelectric Response to Coherent Longitudinal and Transverse Acoustic Phonons in a Semiconductor Schottky Diode

    Science.gov (United States)

    Srikanthreddy, D.; Glavin, B. A.; Poyser, C. L.; Henini, M.; Lehmann, D.; Jasiukiewicz, Cz.; Akimov, A. V.; Kent, A. J.

    2017-02-01

    We study the generation of microwave electronic signals by pumping a (311) GaAs Schottky diode with compressive and shear acoustic phonons, generated by the femtosecond optical excitation of an Al film transducer and mode conversion at the Al-GaAs interface. They propagate through the substrate and arrive at the Schottky device on the opposite surface, where they induce a microwave electronic signal. The arrival time, the amplitude, and the polarity of the signals depend on the phonon mode. A theoretical analysis is made of the polarity of the experimental signals. This analysis includes the piezoelectric and deformation potential mechanisms of electron-phonon interaction in a Schottky contact and shows that the piezoelectric mechanism is dominant for both transverse and longitudinal modes with frequencies below 250 and 70 GHz, respectively.

  17. [Noncontact and noninvasive microwave biological measurements].

    Science.gov (United States)

    Misawa, T; Kutsumi, Y; Tada, H; Kim, S S; Nakai, T; Miyabo, S; Hamada, T; Arai, I; Suzuki, T

    1990-01-01

    Without contact probes, the signals of small human body surface movements were obtained with microwave Doppler sensors using a two-phase interferometric method. The signals were then compared with mechanocardiographic records routinely obtained by contact transducers. Furthermore, this system was applied to patients wearing clothes. The study subjects consisted of 20 cardiac patients and 10 normal controls. 1. The microwave signals obtained in the cervical and precordial regions were similar to those of the mechanocardiographic recordings, such as the carotid pulse and jugular venous pulse tracings and the apexcardiogram. There was a significant correlation between left ventricular ejection time (LVET) obtained by microwave Doppler sensors and that by the carotid pulse tracing (r = 0.95). 2. The signals of the microwave Doppler sensor were obtained from the patients wearing clothes. The heart beat components were distinguished from respiratory motion and patients' movements using band-pass filters. These results suggest that this method is capable of evaluating cardiac function noninvasively and thus has a distinct advantage in the field of non-contact measurements.

  18. Orthogonal linear polarization tunable-beat ring laser with a superluminescent diode.

    Science.gov (United States)

    Takahashi, Y; Yoshino, T

    1997-09-20

    An orthogonal linear polarization operated ring laser with a superluminescent diode has been demonstrated to generate a tunable optical beat signal. The ring cavity contains a superluminescent diode as the optical gain medium, Faraday rotators, and a variable phase retarder (Babinet-Soleil compensator). By controlling the retarder, we changed the beat frequency in the range from a few tens of megahertz to 100 MHz.

  19. Orthogonal linear polarization tunable-beat ring laser with a superluminescent diode

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Y.; Yoshino, T. [Department of Electronic Engineering, Faculty of Engineering, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376 (Japan)

    1997-09-01

    An orthogonal linear polarization operated ring laser with a superluminescent diode has been demonstrated to generate a tunable optical beat signal. The ring cavity contains a superluminescent diode as the optical gain medium, Faraday rotators, and a variable phase retarder (Babinet-Soleil compensator). By controlling the retarder, we changed the beat frequency in the range from a few tens of megahertz to 100 MHz. {copyright} 1997 Optical Society of America

  20. The Cosmic Microwave Background

    Directory of Open Access Journals (Sweden)

    Jones Aled

    1998-01-01

    Full Text Available We present a brief review of current theory and observations of the cosmic microwave background (CMB. New predictions for cosmological defect theories and an overview of the inflationary theory are discussed. Recent results from various observations of the anisotropies of the microwave background are described and a summary of the proposed experiments is presented. A new analysis technique based on Bayesian statistics that can be used to reconstruct the underlying sky fluctuations is summarised. Current CMB data is used to set some preliminary constraints on the values of fundamental cosmological parameters $Omega$ and $H_circ$ using the maximum likelihood technique. In addition, secondary anisotropies due to the Sunyaev-Zel'dovich effect are described.

  1. Microwave Processing of Materials

    Science.gov (United States)

    1994-01-01

    Pennsylvania: Materials Research Society. Wagner, C., and W. Schottky. 1930. Zeitschrift fuer Physikalische Chemie. BL11:163. Walkiewicz, J. W., A. E. Clark...Science and Engineering. 66:468--469. Bloch, F. 1928. Zeitschrift fuer Physik. 52:555. Boch, P., N. Lequeux and P. Piluso. 1992. Reaction Sintering...Frankel, J. 1926. Zeitschrift fuer Physik. 35:652. Fukushima, H., T. Yamaka, and M. Matsui. 1990. Microwave Heating of Ceramics and its Application to

  2. SUNIST Microwave Power System

    Institute of Scientific and Technical Information of China (English)

    Feng Songlin; Yang Xuanzong; Feng Chunhua; Wang Long; Rao Jun; Feng Kecheng

    2005-01-01

    Experiments on the start-up and formation of spherical tokamak plasmas by electron cyclotron heating alone without ohmic heating and electrode discharge assisted electron cyclotron wave current start-up will be carried out on the SUNIST (Sino United Spherical Tokamak) device.The 2.45 GHz/100 kW/30 ms microwave power system and 1000 V/50 A power supply for electrode discharge are ready for experiments with non-inductive current drive.

  3. Microwave Multicomponent Synthesis

    Directory of Open Access Journals (Sweden)

    Helmut M. Hügel

    2009-12-01

    Full Text Available In the manner that very important research is often performed by multidisciplinary research teams, the applications of multicomponent reactions involving the combination of multiple starting materials with different functional groups leading to the higher efficiency and environmentally friendly construction of multifunctional/complex target molecules is growing in importance. This review will explore the advances and advantages in microwave multicomponent synthesis (MMS that have been achieved over the last five years.

  4. CURING OF POLYMERIC COMPOSITES USING MICROWAVE RESIN TRANSFER MOULDING (RTM

    Directory of Open Access Journals (Sweden)

    R. YUSOFF

    2007-08-01

    Full Text Available The main objective of this work is to compare the difference between microwave heating and conventional thermal heating in fabricating carbon/epoxy composites. Two types of epoxy resin systems were used as matrices, LY5052-HY5052 and DGEBA-HY917-DY073. All composite samples were fabricated using resin transfer moulding (RTM technique. The curing of the LY5052-HY5052-carbon and the DGEBA-HY917-DY073-carbon composite systems, were carried out at 100 °C and 120 °C, respectively. Microwave heating showed better temperature control than conventional heating, however, the heating rate of the microwave cured samples were slower than the conventionally cured samples. This was attributed to the lower power (250 W used when heating with microwaves compared to 2000 W used in conventional heating. Study of thermal characteristics as curing progressed showed that the polymerisation reaction occurred at a faster rate during microwave curing than in conventional curing for both the DGEBA and the LY/HY5052 carbon composite systems. The actual cure cycle was reduced from 60 minutes to 40 minutes when using microwaves for curing DGEBA-carbon composites. As for LY/HY5052-carbon composites, the actual cure cycle was reduced from 3 hours to 40 minutes. Both conventional and microwave heating yielded similar glass transition temperatures (120 °C for DGEBA systems and 130 °C for LY/HY5052 systems. Microwave cured composites had higher void contents than conventionally cured composites (2.2-2.8% and 1.8-2.4% for DGEBA and LY/HY5052 microwave cured composites, respectively, compared to 0.2-0.4% for both DGEBA and LY/HY5052 thermally cured composites. C-scan traces showed that all composites, regardless of methods of curing, had minimal defects.

  5. Contrast-enhanced microwave detection and treatment of breast cancer

    Science.gov (United States)

    Gao, Fuqiang

    Contrast agents and heating agents have been proposed for microwave breast tumor imaging and treatment, respectively. The dielectric properties of the tumor are altered with contrast agents or heating agents that locally accumulate in the tumor. The resulting change in dielectric properties of the tumor has the potential to enhance the sensitivity of microwave imaging of breast tumors and increase the efficiency and selectivity of microwave thermal therapy of breast tumors. This dissertation addresses several key challenges in contrast-enhanced microwave imaging and treatment of breast tumors. Carbon nanotubes (CNTs) have been shown to enhance both the relative permittivity and effective conductivity of the host medium, and are promising as theranostic (integrated therapeutic and diagnostic) agents. Thus, our properties characterization work focuses on CNT dispersions. We performed in vitro microwave dielectric properties and heating response characterization of dispersions of CNTs treated by different functionalization methods and identified a CNT formulation that is very promising as a microwave theranostic agent. Stable dispersions of CNTs with concentrations up to 20 mg/ml are obtained with this formulation, and the enhanced microwave properties of these dispersions are extraordinary compared to the control. We also conducted in vivo dielectric properties characterization of mouse tumors with intra-tumoral injections of CNT dispersions and confirmed that the presence of CNTs increases the dielectric properties of the tumor. In parallel, we developed a contrast-enhanced microwave breast tumor imaging algorithm using sparse reconstruction methods. We demonstrated that this algorithm accurately localizes small tumors in 3D numerical breast phantoms. We also demonstrated the experimental feasibility of this method using physical breast phantoms. Lastly, we studied the sensitivity of the distorted Born iterative method (DBIM) to initial guesses and developed a

  6. Optimum Barrier Height for SiC Schottky Barrier Diode

    OpenAIRE

    Mohamed Abd El-Latif; Alaa El-Din Sayed Hafez

    2013-01-01

    The study of barrier height control and optimization for Schottky barrier diode (SBD) from its physical parameters have been introduced using particle swarm optimization (PSO) algorithm. SBD is the rectifying barrier for electrical conduction across the metal semiconductor (MS) junction and, therefore, is of vital importance to the successful operation of any semiconductor device. 4H-SiC is used as a semiconductor material for its good electrical characteristics with high-power semiconductor ...

  7. Microwave sterilization method and apparatus

    OpenAIRE

    V. N. Vasilenko; Minuhin, V. V.; Podorozhnyak, A. A.; Trubaev, S. I.

    1995-01-01

    Experience of industrially developed countries in utilization of microwave radiation has been analyzed. Apparatus for realization of microwave method of sterilization has been designed. A number of experiments for the estimation of bactericidal, sporacidal, and virusidal properties of microwave radiation action has been carried out in 3 to 13 cm wavelength band. B. Lycheniform shtumm G., B. Subtilis ATTC 6633, E. Coli ATTC 25922 and bacterial virus FX 174 were used as test microbes. Effect of...

  8. Introduction to Microwave Linear [Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Whittum, David H

    1999-01-04

    The elements of microwave linear accelerators are introduced starting with the principles of acceleration and accelerating structures. Considerations for microwave structure modeling and design are developed from an elementary point of view. Basic elements of microwave electronics are described for application to the accelerator circuit and instrumentation. Concepts of beam physics are explored together with examples of common beamline instruments. Charged particle optics and lattice diagnostics are introduced. Considerations for fixed-target and colliding-beam experimentation are summarized.

  9. Microwave-Assisted Olefin Metathesis

    Science.gov (United States)

    Nicks, François; Borguet, Yannick; Sauvage, Xavier; Bicchielli, Dario; Delfosse, Sébastien; Delaude, Lionel; Demonceau, Albert

    Since the first reports on the use of microwave irradiation to accelerate organic chemical transformations, a plethora of papers have been published in this field. In most examples, microwave heating has been shown to dramatically reduce reaction times, increase product yields, and enhance product purity by reducing unwanted side reactions compared to conventional heating methods. The present contribution aims at illustrating the advantages of this technology in olefin metathesis and, when data are available, at comparing microwave-heated and conventionally heated experiments

  10. Numerical modeling of microwave heating

    Directory of Open Access Journals (Sweden)

    Shukla A.K.

    2010-01-01

    Full Text Available The present study compares the temperature distribution within cylindrical samples heated in microwave furnace with those achieved in radiatively-heated (conventional furnace. Using a two-dimensional finite difference approach the thermal profiles were simulated for cylinders of varying radii (0.65, 6.5, and 65 cm and physical properties. The influence of susceptor-assisted microwave heating was also modeled for the same. The simulation results reveal differences in the heating behavior of samples in microwaves. The efficacy of microwave heating depends on the sample size and its thermal conductivity.

  11. The Microwave SQUID Multiplexer

    Science.gov (United States)

    Mates, John Arthur Benson

    2011-12-01

    This thesis describes a multiplexer of Superconducting Quantum Interference Devices (SQUIDs) with low-noise, ultra-low power dissipation, and great scalability. The multiplexer circuit measures the magnetic flux in a large number of unshunted rf SQUIDs by coupling each SQUID to a superconducting microwave resonator tuned to a unique resonance frequency and driving the resonators from a common feedline. A superposition of microwave tones measures each SQUID simultaneously using only two coaxial cables between the cryogenic device and room temperature. This multiplexer will enable the instrumentation of arrays with hundreds of thousands of low-temperature detectors for new applications in cosmology, materials analysis, and nuclear non-proliferation. The driving application of the Microwave SQUID Multiplexer is the readout of large arrays of superconducting transition-edge sensors, by some figures of merit the most sensitive detectors of electromagnetic signals over a span of more than nine orders of magnitude in energy, from 40 GHz microwaves to 200 keV gamma rays. Modern transition-edge sensors have noise-equivalent power as low as 10-20 W / Hz1/2 and energy resolution as good as 2 eV at 6 keV. These per-pixel sensitivities approach theoretical limits set by the underlying signals, motivating a rapid increase in pixel count to access new science. Compelling applications, like the non-destructive assay of nuclear material for treaty verification or the search for primordial gravity waves from inflation use arrays of these detectors to increase collection area or tile a focal plane. We developed three generations of SQUID multiplexers, optimizing the first for flux noise 0.17 muPhi0 / Hz1/2, the second for input current noise 19 pA / Hz1/2, and the last for practical multiplexing of large arrays of cosmic microwave background polarimeters based on transition-edge sensors. Using the last design we demonstrated multiplexed readout of prototype polarimeters with the

  12. Destructive Single-Event Effects in Diodes

    Science.gov (United States)

    Casey, Megan C.; Lauenstein, Jean-Marie; Campola, Michael J.; Wilcox, Edward P.; Phan, Anthony M.; Label, Kenneth A.

    2017-01-01

    In this work, we discuss the observed single-event effects in a variety of types of diodes. In addition, we conduct failure analysis on several Schottky diodes that were heavy-ion irradiated. High- and low-magnitude optical microscope images, infrared camera images, and scanning electron microscope images are used to identify and describe the failure locations.

  13. Materials for diode pumped solid state lasers

    Science.gov (United States)

    Chase, L. L.; Davis, L. E.; Krupke, W. F.; Payne, S. A.

    1991-07-01

    The advantages of semiconductor diode lasers and laser arrays as pump sources for solid state lasers are reviewed. The properties that are desirable in solid state laser media for various diode pumping applications are discussed, and the characteristics of several promising media are summarized.

  14. Temperature dependence of commercially available diode detectors.

    Science.gov (United States)

    Saini, Amarjit S; Zhu, Timothy C

    2002-04-01

    Temperature dependence of commercially available n- and p-type diodes were studied experimentally under both high instantaneous dose rate (pulsed) and low dose rate (continuous) radiation. The sensitivity versus temperature was measured at SSD = 80 or 100 cm, 10 x 10 cm2, and 5 cm depth in a 30 x 30 x 30 cm3 water phantom between 10 degrees C and 35 degrees C. The response was linear for all the diode detectors. The temperature coefficient (or sensitivity variation with temperature, svwt) was dose rate independent for preirradiated diodes. They were (0.30 +/- 0.01)%/degrees C, (0.36 +/- 0.03)%/degrees C, and (0.29 +/- 0.08)%/degrees C for QED p-type, EDP p-type, and Isorad n-type diodes, respectively. The temperature coefficient for unirradiated n-type diodes was different under low dose rate [(0.16 to 0.45)%/degrees C, continuous, cobalt] and high instantaneous dose rate [(0.07 +/- 0.02)%/degrees C, pulsed radiation]. Moreover, the temperature coefficient varies among individual diodes. Similarly, the temperature coefficient for a special unirradiated QED p-type diode was different under low dose rate (0.34%/degrees C, cobalt) and high instantaneous dose rate [(0.26 +/- 0.01)%/degrees C, pulsed radiation]. Sufficient preirradiation can eliminate dose rate dependence of the temperature coefficient. On the contrary, preirradiation cannot eliminate dose rate dependence of the diode sensitivity itself.

  15. Effect of band gap narrowing on GaAs tunnel diode I-V characteristics

    Science.gov (United States)

    Lebib, A.; Hannanchi, R.; Beji, L.; EL Jani, B.

    2016-12-01

    We report on experimental and theoretical study of current-voltage characteristics of C/Si-doped GaAs tunnel diode. For the investigation of the experimental data, we take into account the band-gap narrowing (BGN) effect due to heavily-doped sides of the tunnel diode. The BGN of the n- and p-sides of tunnel diode was measured by photoluminescence spectroscopy. The comparison between theoretical results and experimental data reveals that BGN effect enhances tunneling currents and hence should be considered to identify more accurately the different transport mechanisms in the junction. For C/Si-doped GaAs tunnel diode, we found that direct tunneling is the dominant transport mechanism at low voltages. At higher voltages, this mechanism is replaced by the rate-controlling tunneling via gap states in the forbidden gap.

  16. Effect of band gap narrowing on GaAs tunnel diode I-V characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Lebib, A.; Hannanchi, R. [Laboratoire d' énergie et de matériaux, LabEM-LR11ES34-Université de sousse (Tunisia); Beji, L., E-mail: lotbej_fr@yahoo.fr [Laboratoire d' énergie et de matériaux, LabEM-LR11ES34-Université de sousse (Tunisia); EL Jani, B. [Unité de Recherche sur les Hétéro-Epitaxies et Applications, Faculté des Sciences, Université de Monastir, 5019 Monastir (Tunisia)

    2016-12-01

    We report on experimental and theoretical study of current-voltage characteristics of C/Si-doped GaAs tunnel diode. For the investigation of the experimental data, we take into account the band-gap narrowing (BGN) effect due to heavily-doped sides of the tunnel diode. The BGN of the n- and p-sides of tunnel diode was measured by photoluminescence spectroscopy. The comparison between theoretical results and experimental data reveals that BGN effect enhances tunneling currents and hence should be considered to identify more accurately the different transport mechanisms in the junction. For C/Si-doped GaAs tunnel diode, we found that direct tunneling is the dominant transport mechanism at low voltages. At higher voltages, this mechanism is replaced by the rate-controlling tunneling via gap states in the forbidden gap.

  17. Microwave generation enhancement of X-band CRBWO by use of coaxial dual annular cathodes

    Directory of Open Access Journals (Sweden)

    Yan Teng

    2013-07-01

    Full Text Available This paper presents an approach that greatly enhances both the output power and the conversion efficiency of the coaxial relativistic backward wave oscillator (CRBWO by using coaxial dual annular cathodes, which increases the diode current rather than the diode voltage. The reasons for the maladjustment of CRBWO under a high diode voltage are analyzed theoretically. It is found that by optimization of the diode structure, the shielding effect of the space charge of the outer beams on the inner cathode can be alleviated effectively and dual annular beams with the same kinetic energy can be explosively emitted in parallel. The coaxial reflector can enhance the conversion efficiency by improving the premodulation of the beams. The electron dump on the inner conductor ensures that the electron beams continue to provide kinetic energy to the microwave output until they vanish. Particle-in-cell (PIC simulation results show that generation can be enhanced up to an output power level of 3.63 GW and conversion efficiency of 45% at 8.97 GHz under a diode voltage of 659 kV and current of 12.27 kA. The conversion efficiency remains above 40% and the output frequency variation is less than 100 MHz over a voltage range of more than 150 kV. Also, the application of the coaxial dual annular cathodes means that the diode impedance is matched to that of the transmission line of the accelerators. This impedance matching can effectively eliminate power reflection at the diode, and thus increase the energy efficiency of the entire system.

  18. Non-Ionizing Radiation Used in Microwave Ovens

    Science.gov (United States)

    ... in Microwave Ovens Non-Ionizing Radiation Used in Microwave Ovens Explore the interactive, virtual community of RadTown USA ! ... learn more About Non-Ionizing Radiation Used in Microwave Ovens Microwave Oven. Microwave ovens use electromagnetic waves that ...

  19. Mechanism of microwave sterilization in the dry state.

    Science.gov (United States)

    Jeng, D K; Kaczmarek, K A; Woodworth, A G; Balasky, G

    1987-01-01

    With an automated computerized temperature control and a specialized temperature measurement system, dry spores of Bacillus subtilis subsp. niger were treated with heat simultaneously in a convection dry-heat oven and a microwave oven. The temperature of the microwave oven was monitored such that the temperature profiles of the spore samples in both heat sources were nearly identical. Under these experimental conditions, we unequivocally demonstrated that the mechanism of sporicidal action of the microwaves was caused solely by thermal effects. Nonthermal effects were not significant in a dry microwave sterilization process. Both heating systems showed that a dwelling time of more than 45 min was required to sterilize 10(5) inoculated spores in dry glass vials at 137 degrees C. The D values of both heating systems were 88, 14, and 7 min at 117, 130, and 137 degrees C, respectively. The Z value was estimated to be 18 degrees C. PMID:3118807

  20. Microwave Disinfection in a Ventilation and Air-Conditioning System

    Institute of Scientific and Technical Information of China (English)

    LU Zhen; ZHANG Ji-li; MA Liang-dong; HE Juan

    2009-01-01

    Because of its broad spectrum and high efficiency,the microwave disinfection was used to control the airborne microbial contaminates in VAC system.Some microwave disinfection devices were developed com-bined with air filter,the design and calculation method was presented,and the disinfection effects on White staphylococcus,Staphylococcus aureus,Bacillus Subtilis,Escherichi coli were measured.The results show that the major influence factors on disinfection effect are microwave power,water-content of filter material,dis-infecting duration.After 15 min,the kill ratio is>90%,and the log value is>1.The microwave field is uni-form and the kill effect of bacteria on each surface of filter is the same,without statistically significant differ-ence.

  1. Microwave Plasma Hydrogen Recovery System

    Science.gov (United States)

    Atwater, James; Wheeler, Richard, Jr.; Dahl, Roger; Hadley, Neal

    2010-01-01

    A microwave plasma reactor was developed for the recovery of hydrogen contained within waste methane produced by Carbon Dioxide Reduction Assembly (CRA), which reclaims oxygen from CO2. Since half of the H2 reductant used by the CRA is lost as CH4, the ability to reclaim this valuable resource will simplify supply logistics for longterm manned missions. Microwave plasmas provide an extreme thermal environment within a very small and precisely controlled region of space, resulting in very high energy densities at low overall power, and thus can drive high-temperature reactions using equipment that is smaller, lighter, and less power-consuming than traditional fixed-bed and fluidized-bed catalytic reactors. The high energy density provides an economical means to conduct endothermic reactions that become thermodynamically favorable only at very high temperatures. Microwave plasma methods were developed for the effective recovery of H2 using two primary reaction schemes: (1) methane pyrolysis to H2 and solid-phase carbon, and (2) methane oligomerization to H2 and acetylene. While the carbon problem is substantially reduced using plasma methods, it is not completely eliminated. For this reason, advanced methods were developed to promote CH4 oligomerization, which recovers a maximum of 75 percent of the H2 content of methane in a single reactor pass, and virtually eliminates the carbon problem. These methods were embodied in a prototype H2 recovery system capable of sustained high-efficiency operation. NASA can incorporate the innovation into flight hardware systems for deployment in support of future long-duration exploration objectives such as a Space Station retrofit, Lunar outpost, Mars transit, or Mars base. The primary application will be for the recovery of hydrogen lost in the Sabatier process for CO2 reduction to produce water in Exploration Life Support systems. Secondarily, this process may also be used in conjunction with a Sabatier reactor employed to

  2. Laser diode package with enhanced cooling

    Science.gov (United States)

    Deri, Robert J.; Kotovsky, Jack; Spadaccini, Christopher M.

    2011-09-13

    A laser diode package assembly includes a reservoir filled with a fusible metal in close proximity to a laser diode. The fusible metal absorbs heat from the laser diode and undergoes a phase change from solid to liquid during the operation of the laser. The metal absorbs heat during the phase transition. Once the laser diode is turned off, the liquid metal cools off and resolidifies. The reservoir is designed such that that the liquid metal does not leave the reservoir even when in liquid state. The laser diode assembly further includes a lid with one or more fin structures that extend into the reservoir and are in contact with the metal in the reservoir.

  3. Microwave Plasma System: PVA Tepla 300

    Data.gov (United States)

    Federal Laboratory Consortium — Description: CORAL Name: Microwave Asher A tool using microwave oxygen plasma to remove organics on the surfaces Specifications / Capabilities: Frequency: 2.45 GHz...

  4. High peak-to-valley current ratio In0.53Ga0.47As/AlAs resonant tunneling diode with a high doping emitter

    Institute of Scientific and Technical Information of China (English)

    Wang Wei; Sun Hao; Teng Teng; Sun Xiaowei

    2012-01-01

    An In0.53Ga0.47As/AlAs resonant tunneling diode (RTD) with a high doping emitter is designed and fabricated using air bridge technology.The RTD exhibits a high peak-to-valley current ratio (PVCR) of more than 40 at room temperature,with a peak current density of 24 kA/cm2.The extraction of device parameters from DC and microwave measurements is presented together with an RTD equivalent circuit.The high PVCR RTD with small intrinsic capacitance is favorable for microwave/THz applications.

  5. The European Microwave Week 2008 and its Microwave Conferences

    NARCIS (Netherlands)

    Hoogeboom, P.; Van Vliet, F.

    2009-01-01

    Under the auspices of the European Microwave Association (EuMA) the 11th annual European Microwave Week was organized in the Amsterdam RAI Congress Centre, The Netherlands, 27-31 October 2008. This major event consisted this year of five conferences, an exhibition, and various side events. The 38th

  6. Hermetic diode laser transmitter module

    Science.gov (United States)

    Ollila, Jyrki; Kautio, Kari; Vahakangas, Jouko; Hannula, Tapio; Kopola, Harri K.; Oikarinen, Jorma; Sivonen, Matti

    1999-04-01

    In very demanding optoelectronic sensor applications it is necessary to encapsulate semiconductor components hermetically in metal housings to ensure reliable operation of the sensor. In this paper we report on the development work to package a laser diode transmitter module for a time- off-light distance sensor application. The module consists of a lens, laser diode, electronic circuit and optomechanics. Specifications include high acceleration, -40....+75 degree(s)C temperature range, very low gas leakage and mass-production capability. We have applied solder glasses for sealing optical lenses and electrical leads hermetically into a metal case. The lens-metal case sealing has been made by using a special soldering glass preform preserving the optical quality of the lens. The metal housings are finally sealed in an inert atmosphere by welding. The assembly concept to retain excellent optical power and tight optical axis alignment specifications is described. The reliability of the laser modules manufactured has been extensively tested using different aging and environmental test procedures. Sealed packages achieve MIL- 883 standard requirements for gas leakage.

  7. Preliminary experimental investigation of an X-band Cerenkov-type high power microwave oscillator without guiding magnetic field

    Science.gov (United States)

    Guo, Liming; Shu, Ting; Li, Zhiqiang; Ju, Jinchuan; Fang, Xiaoting

    2017-02-01

    Among high power microwave (HPM) generators without guiding magnetic field, Cerenkov-type oscillator is expected to achieve a relatively high efficiency, which has already been realized in X-band in our previous simulation work. This paper presents the preliminary experimental investigations into an X-band Cerenkov-type HPM oscillator without guiding magnetic field. Based on the previous simulation structure, some modifications regarding diode structure were made. Different cathode structures and materials were tested in the experiments. By using a ring-shaped graphite cathode, microwave of about one hundred megawatt level was generated with a pure center frequency of 9.14 GHz, and an efficiency of about 1.3%. As analyzed in the paper, some practical issues reduce the efficiency in experiments, such as real features of the electron beam, probable breakdown regions on the cathode surface which can damage the diode, and so forth.

  8. Investigating a Hypothetical Semiconductor Laser Bar with a Damaged Single Emitter Using a Laser Diode Simulation/Emulation Tool

    Directory of Open Access Journals (Sweden)

    C.K. Amuzuvi

    2014-02-01

    Full Text Available This study demonstrates the use of Barlase, a semiconductor laser diode emulation tool, to emulate the by-emitter degradation of high power semiconductor laser diodes.Barlase is software that uses a LabView control interface. In this study, a hypothetical laser diode bar (multiple emitters was used to investigate a damaged single emitter randomly located in the bar and its behavior analyzed within the bar. It should however, be noted that, this scenario is valid for devices at the start of the aging process only. When all other relevant effects that affect the performance of laser diodes bars are allowed to interact over time, high levels of defects can also play important role in the degradation process. The results of this simulation scenario show the successful implementation of Barlase in the by-emitter analysis of laser diodes.

  9. Heating performance investigation of a bidirectional partition fluid thermal diode

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Xiande; Xia, Lulu [Institute of Air Conditioning and Refrigeration, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing, Jiangsu Province 210016 (China)

    2010-03-15

    A novel thermal diode, bidirectional partition fluid thermal diode (BPFTD) that is fabricated by integrating a thermal insulation partition and a movable control blade into a water tank, is proposed. The bidirectional configuration allows the BPFTD to serve both passive solar heating in winter and passive cooling in summer. BPFTD heating performances are tested with two side-by-side hot boxes and compared experimentally with a water-wall having optimum thickness. Two stages of experiments are conducted. The first stage is to investigate an appropriate position of BPFTD partition, and the second compares the BPFTD with the water-wall. The test results show that the BPFTD has much better heating performances than the water-wall. Analysis indicates that the BPFTD may increase heat supply by around 140% when a single glazing cover without night insulation is used and by around 70% in case of using a double glazing cover without night insulation. (author)

  10. Use of laser diodes in cavity ring-down spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zare, R.N.; Paldus, B.A.; Ma, Y.; Xie, J. [Stanford Univ., CA (United States)

    1997-12-31

    We have demonstrated that cavity ring-down spectroscopy (CRDS), a highly sensitive absorption technique, is versatile enough to serve as a complete diagnostic for materials process control. In particular, we have used CRDS in the ultraviolet to determine the concentration profile of methyl radicals in a hot-filament diamond reactor; we have applied CRDS in the mid-infrared to detect 50 ppb of methane in a N{sub 2} environment; and, we have extended CRDS so that we can use continuous-wave diode laser sources. Using a laser diode at 810 nm, we were able to achieve a sensitivity of 2 x 10{sup -8} cm{sup -1}. Thus, CRDS can be used not only as an in situ diagnostic for investigating the chemistry of diamond film deposition, but it can also be used as a gas purity diagnostic for any chemical vapor deposition system.

  11. A Design of Intelligent Energy-saving Drinking Water Machine Based on TX982 Microwave Induction Controller%基于TX982微波感应控制器智能节能饮水机的设计

    Institute of Scientific and Technical Information of China (English)

    杨芳

    2015-01-01

    After being switched on, the drinking water machine is always at heating or warm-keeping state, no matter whether there are people in the room. The water is repeatedly heated, which does harm to people’s health and wastes electricity as well. In view of the above problem, the drinking water machine is improved, based on TX982 microwave induction controller. The new machine can detect people’s activities in the room or people’s short going-by, which helps the machine to control the water-heating time. In this way, the new drinking water machine has the intelligent and energy-saving functions.%饮水机接通电源,不管房间内有没有人都始终处于加热或保温状态,并且水被反复加热,结果危害人身体健康,浪费电能。针对以上情况,本文主要讲述了如何应用TX982微波感应控制器对饮水机进行改造,来自动检测房间有无人员活动及是否短暂经过情况,控制加热时间,实现饮水机具有智能化及节能功能。

  12. Flatness-based pre-compensation of laser diodes

    CERN Document Server

    Rouchon, A Abichou S Elasmi P

    2007-01-01

    A physical nonlinear dynamical model of a laser diode is considered. We propose a feed-forward control scheme based on differential flatness for the design of input-current modulations to compensate diode distortions. The goal is to transform without distortion a radio-frequency current modulation into a light modulation leaving the laser-diode and entering an optic fiber. We prove that standard physical dynamical models based on dynamical electron and photons balance are flat systems when the current is considered as control input, the flat output being the photon number (proportional to the light power). We prove that input-current is an affine map of the flat output, its logarithm and their time-derivatives up to order two. When the flat output is an almost harmonic signal with slowly varying amplitude and phase, these derivatives admit precise analytic approximations. It is then possible to design simple analogue electronic circuits to code approximations of the nonlinear computations required by our flat...

  13. Microwave Sterilization in School Microbiology.

    Science.gov (United States)

    Wynn, Brian; Dixon, Angela

    1988-01-01

    Described are two investigations carried out in a high school biology department using a domestic microwave oven to compare the relative attributes of the autoclave and microwave oven in school use. Discussed are equipment, methods, and results of each investigation. (Author/CW)

  14. More Experiments with Microwave Ovens

    Science.gov (United States)

    Vollmer, Michael; Mollmann, Klaus-Peter; Karstadt, Detlef

    2004-01-01

    Microwave ovens can be used to perform exciting demonstrations that illustrate a variety of physics topics. Experiments discussed here show superheating, visualize the inhomogeneous heating that takes place in a microwave and also show how to use a mobile phone to detect radiation leaking from the oven. Finally eggs can give some spectacular…

  15. More Experiments with Microwave Ovens

    Science.gov (United States)

    Vollmer, Michael; Mollmann, Klaus-Peter; Karstadt, Detlef

    2004-01-01

    Microwave ovens can be used to perform exciting demonstrations that illustrate a variety of physics topics. Experiments discussed here show superheating, visualize the inhomogeneous heating that takes place in a microwave and also show how to use a mobile phone to detect radiation leaking from the oven. Finally eggs can give some spectacular…

  16. Study on chromatographic fingerprint of sarcandra glabra (Thunb.) by microwave-assisted extraction coupled to HPLC/DAD

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Microwave-assisted extraction(MAE)was used for extraction of effective components of sarcandra glabra(Thunb.),and then chromatographic fingerprint of sarcandra glabra(Thunb.)was studied by high performance liquid chromatography/diode array detector(HPLC/DAD).The conditions of MAE were optimized by an orthogonal experiment,and then the authentication and validation of the chromatographic fingerprint were conducted.Nine peaks were identified as common peaks in the fingerprint chromatograms,and isofraxidin was...

  17. Microwave milk pasteurization without food safety risk

    Directory of Open Access Journals (Sweden)

    Gábor Géczi

    2013-02-01

    Full Text Available 96 Normal 0 false false false CS JA X-NONE According to nutrition science, milk and milk products are essential food for humans. The primary processing of milk includes its storage, separation, homogenization and the pasteurization process as well. The latter is a kind of heat treatment, which has been used to extend the storage life of food since the late 18th century. Although heat treatment of milk can be achieved through the use of microwave technology, the inhomogeneity of electromagnetic fields leads to an uneven distribution of temperature in the food products, therefore precluding their use in industry. The pasteurization operation is very often Critical Controll Point (CCP according of food safety systems. In recent years our research team has developed continuously operating heat treatment pilot-plant equipment, capable of measuring and contrasting the effects of different heat treatment methods, such as thermostat-controlled water baths and microwave energy, on liquid food products. We examined and compared protein, fat and bacterial content in samples of fresh cow milk with heat-treated cow milk samples. In addition, storage experiments were carried out under a microscope and recordings made of fat globules. Our results so far show that the microwave heat treatment is equivalent to the convection manner pasteurization technology, as we found no difference between the heat-treated products.doi:10.5219/260

  18. Electrically tunable materials for microwave applications

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Aftab, E-mail: aahmed@anl.gov; Goldthorpe, Irene A.; Khandani, Amir K. [Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2015-03-15

    Microwave devices based on tunable materials are of vigorous current interest. Typical applications include phase shifters, antenna beam steering, filters, voltage controlled oscillators, matching networks, and tunable power splitters. The objective of this review is to assist in the material selection process for various applications in the microwave regime considering response time, required level of tunability, operating temperature, and loss tangent. The performance of a variety of material types are compared, including ferroelectric ceramics, polymers, and liquid crystals. Particular attention is given to ferroelectric materials as they are the most promising candidates when response time, dielectric loss, and tunability are important. However, polymers and liquid crystals are emerging as potential candidates for a number of new applications, offering mechanical flexibility, lower weight, and lower tuning voltages.

  19. Tunable Magnetic Resonance in Microwave Spintronics Devices

    Science.gov (United States)

    Chen, Yunpeng; Fan, Xin; Xie, Yunsong; Zhou, Yang; Wang, Tao; Wilson, Jeffrey D.; Simons, Rainee N.; Chui, Sui-Tat; Xiao, John Q.

    2015-01-01

    Magnetic resonance is one of the key properties of magnetic materials for the application of microwave spintronics devices. The conventional method for tuning magnetic resonance is to use an electromagnet, which provides very limited tuning range. Hence, the quest for enhancing the magnetic resonance tuning range without using an electromagnet has attracted tremendous attention. In this paper, we exploit the huge exchange coupling field between magnetic interlayers, which is on the order of 4000 Oe and also the high frequency modes of coupled oscillators to enhance the tuning range. Furthermore, we demonstrate a new scheme to control the magnetic resonance frequency. Moreover, we report a shift in the magnetic resonance frequency as high as 20 GHz in CoFe based tunable microwave spintronics devices, which is 10X higher than conventional methods.

  20. Passive Microwave Components and Antennas

    DEFF Research Database (Denmark)

    State-of-the-art microwave systems always require higher performance and lower cost microwave components. Constantly growing demands and performance requirements of industrial and scientific applications often make employing traditionally designed components impractical. For that reason, the design...... and development process remains a great challenge today. This problem motivated intensive research efforts in microwave design and technology, which is responsible for a great number of recently appeared alternative approaches to analysis and design of microwave components and antennas. This book highlights...... techniques. Modelling and computations in electromagnetics is a quite fast-growing research area. The recent interest in this field is caused by the increased demand for designing complex microwave components, modeling electromagnetic materials, and rapid increase in computational power for calculation...