WorldWideScience

Sample records for diodes

  1. Liquid diode

    International Nuclear Information System (INIS)

    1976-01-01

    The liquid diode is designed for a flowmeter chamber which has an inlet and an outlet duct, and a flow chamber with a cross-section which is greater than inlet. In the space between the inlet and outlet are two screens with a number of spheres, which may be of different sizes and weights. The screen on the inlet side is smaller than that at the outlet, so that the spheres are able to block the inlet under reverse flow conditions, but do not block the outlet. The system functions as a non-return valve. (G.C.)

  2. 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...

  3. Long pulse diode experiments

    Science.gov (United States)

    McClenahan, Charles R.; Weber, Gerald J.; Omalley, Martin W.; Stewart, Joseph; Rinehart, Larry F.; Buttram, Malcolm T.

    1990-10-01

    A diode employing a thermionic cathode has produced 80 A beams at 200 kV for at least 6 microseconds. Moreover, the diode operates at rates as high as 1 Hz. EGUN simulations of the experimental geometry agree with the experiments. Finally, simulation of a proposed diode geometry predicts a 1 kA, 500 kV beam.

  4. Coaxial foilless diode

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Long; Liu, QingXiang; Li, XiangQiang; Wang, ShaoMeng [College of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031 (China)

    2014-05-15

    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.

  5. 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.

  6. Vortex diode jet

    Science.gov (United States)

    Houck, Edward D.

    1994-01-01

    A fluid transfer system that combines a vortex diode with a jet ejector to transfer liquid from one tank to a second tank by a gas pressurization method having no moving mechanical parts in the fluid system. The vortex diode is a device that has a high resistance to flow in one direction and a low resistance to flow in the other.

  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. Powering laser diode systems

    CERN Document Server

    Trestman, Grigoriy A

    2017-01-01

    This Tutorial Text discusses the competent design and skilled use of laser diode drivers (LDDs) and power supplies (PSs) for the electrical components of laser diode systems. It is intended to help power-electronic design engineers during the initial design stages: the choice of the best PS topology, the calculation of parameters and components of the PS circuit, and the computer simulation of the circuit. Readers who use laser diode systems for research, production, and other purposes will also benefit. The book will help readers avoid errors when creating laser systems from ready-made blocks, as well as understand the nature of the "mystical failures" of laser diodes (and possibly prevent them).

  9. Magnetically insulated H- diodes

    International Nuclear Information System (INIS)

    Fisher, A.; Bystritskii, V.; Garate, E.; Prohaska, R.; Rostoker, N.

    1993-01-01

    At the Univ. of California, Irvine, the authors have been studying the production of intense H - beams using pulse power techniques for the past 7 years. Previously, current densities of H - ions for various diode designs at UCI have been a few A/cm 2 . Recently, they have developed diodes similar to the coaxial design of the Lebedev Physical Institute, Moscow, USSR, where current densities of up to 200 A/cm 2 were reported using nuclear activation of a carbon target. In experiments at UCI employing the coaxial diode, current densities of up to 35 A/cm 2 from a passive polyethylene cathode loaded with TiH 2 have been measured using a pinhole camera and CR-39 track recording plastic. The authors have also been working on a self-insulating, annular diode which can generate a directed beam of H - ions. In the annular diode experiments a plasma opening switch was used to provide a prepulse and a current path which self-insulated the diode. These experiments were done on the machine APEX, a 1 MV, 50 ns, 7 Ω pulseline with a unipolar negative prepulse of ∼ 100 kV and 400 ns duration. Currently, the authors are modifying the pulseline to include an external LC circuit which can generate a bipolar, 150 kV, 1 μs duration prepulse (similar prepulse characteristic as in the Lebedev Institute experiments cited above)

  10. Diode laser pumping

    International Nuclear Information System (INIS)

    Skagerlund, L.E.

    1975-01-01

    A diode laser is pumped or pulsed by a repeated capacitive discharge. A capacitor is periodically charged from a dc voltage source via a transformer, the capacitor being discharged through the diode laser via a controlled switching means after one or more charging periods. During a first interval of each charging period the transformer, while unloaded, stores a specific amount of energy supplied from the dc voltage source. During a subsequent interval of the charging period said specific amount of energy is transmitted from the transformer to the capacitor. The discharging of the capacitor takes place during a first interval of a charging period. (auth)

  11. Diode lasers and arrays

    International Nuclear Information System (INIS)

    Streifer, W.

    1988-01-01

    This paper discusses the principles of operation of III-V semiconductor diode lasers, the use of distributed feedback, and high power laser arrays. The semiconductor laser is a robust, miniature, versatile device, which directly converts electricity to light with very high efficiency. Applications to pumping solid-state lasers and to fiber optic and point-to-point communications are reviewed

  12. Deep diode atomic battery

    International Nuclear Information System (INIS)

    Anthony, T.R.; Cline, H.E.

    1977-01-01

    A deep diode atomic battery is made from a bulk semiconductor crystal containing three-dimensional arrays of columnar and lamellar P-N junctions. The battery is powered by gamma rays and x-ray emission from a radioactive source embedded in the interior of the semiconductor crystal

  13. Infrared diode laser spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Civiš, Svatopluk; Cihelka, Jaroslav; Matulková, Irena

    2010-01-01

    Roč. 18, č. 4 (2010), s. 408-420 ISSN 1230-3402 R&D Projects: GA AV ČR IAA400400705 Institutional research plan: CEZ:AV0Z40400503 Keywords : FTIR spectroscopy * absorption spectroscopy * laser diodes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.027, year: 2010

  14. Diode pumped solid state laser by two diodes

    International Nuclear Information System (INIS)

    Li Mingzhong; Zhang Xiaomin; Liang Yue; Man Yongzai; Zhou Pizhang

    1995-01-01

    A Nd: YLF laser is pumped by home-made quantum well diode lasers. Datum of laser output energy 60 μJ and peak power 120 mw are observed at wavelength 1.047 μm. On the same pumping condition, the output power synchronously pumped by two diodes is higher than the total output power pumped by two diodes separately. The fluctuation is <3%. The results agree with theoretical analysis

  15. Spin-Wave Diode

    Directory of Open Access Journals (Sweden)

    Jin Lan (兰金

    2015-12-01

    Full Text Available A diode, a device allowing unidirectional signal transmission, is a fundamental element of logic structures, and it lies at the heart of modern information systems. The spin wave or magnon, representing a collective quasiparticle excitation of the magnetic order in magnetic materials, is a promising candidate for an information carrier for the next-generation energy-saving technologies. Here, we propose a scalable and reprogrammable pure spin-wave logic hardware architecture using domain walls and surface anisotropy stripes as waveguides on a single magnetic wafer. We demonstrate theoretically the design principle of the simplest logic component, a spin-wave diode, utilizing the chiral bound states in a magnetic domain wall with a Dzyaloshinskii-Moriya interaction, and confirm its performance through micromagnetic simulations. Our findings open a new vista for realizing different types of pure spin-wave logic components and finally achieving an energy-efficient and hardware-reprogrammable spin-wave computer.

  16. 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

  17. Personal neutron diode dosemeter

    International Nuclear Information System (INIS)

    Barthe, J.; Lahaye, T.; Moiseev, T.; Portal, G.

    1993-01-01

    The control and management of neutron doses, received by workers in nuclear power or research facilities, requires a knowledge of cumulated dose equivalent or dose equivalent rate in real time. Individual dosemeters so far developed for this purpose are scarce and not very satisfactory. Passive dosemeters such as TLD systems based on the albedo effect, nuclear emulsions or solid track detectors, do not give sufficiently accurate measurements. Furthermore, the increase in the quality factor and the more restrictive new ICRP recommendations diminish the maximum admissible threshold making currently used systems obsolete. Other than bubble dosemeter systems, based on thermodynamic effects of a superheated gel, no simple electronic device is available at the present time. The development of diode based dosimetric gamma badges, having a size similar to that of credit cards, has stimulated us to design and develop a personal neutron dosemeter based on a double diode system. The results obtained are very encouraging and practical models should become available in the near future. (author)

  18. Polymer light emitting diodes

    International Nuclear Information System (INIS)

    Gautier-Thianche, Emmmanuelle

    1998-01-01

    We study sandwich type semiconducting polymer light emitting diodes; anode/polymer/cathode. ITO is selected as anode, this polymer is a blend of a commercially available polymer with a high hole transport ability: polyvinyl-carbazole and a laser dye: coumarin-515. Magnesium covered with silver is chosen for the anode. We study the influence of polymer thickness and coumarin doping ratio on electroluminescence spectrum, electric characteristics and quantum efficiency. An important drawback is that diodes lifetime remains low. In the second part of our study we determine degradations causes with X-Ray reflectivity experiments. It may be due to ITO very high roughness. We realize a new type of planar electroluminescent device: a channel type electroluminescent device in which polymer layer is inserted into an aluminium channel. Such a device is by far more stable than using classical sandwich structures with the same polymer composition: indeed, charges are generated by internal-field ionization and there is no injection from the electrode to the polymer. This avoids electrochemical reactions at electrodes, thus reducing degradations routes. (author) [fr

  19. Atomic spectroscopy with diode lasers

    International Nuclear Information System (INIS)

    Tino, G.M.

    1994-01-01

    Some applications of semiconductor diode lasers in atomic spectroscopy are discussed by describing different experiments performed with lasers emitting in the visible and in the near-infrared region. I illustrate the results obtained in the investigation of near-infrared transitions of atomic oxygen and of the visible intercombination line of strontium. I also describe how two offset-frequency-locked diode lasers can be used to excite velocity selective Raman transitions in Cs. I discuss the spectral resolution, the accuracy of frequency measurements, and the detection sensitivity achievable with diode lasers. (orig.)

  20. Laterally injected light-emitting diode and laser diode

    Science.gov (United States)

    Miller, Mary A.; Crawford, Mary H.; Allerman, Andrew A.

    2015-06-16

    A p-type superlattice is used to laterally inject holes into an III-nitride multiple quantum well active layer, enabling efficient light extraction from the active area. Laterally-injected light-emitting diodes and laser diodes can enable brighter, more efficient devices that impact a wide range of wavelengths and applications. For UV wavelengths, applications include fluorescence-based biological sensing, epoxy curing, and water purification. For visible devices, applications include solid state lighting and projection systems.

  1. Thermometric Property of a Diode.

    Science.gov (United States)

    Inman, Fred W.; Woodruff, Dan

    1995-01-01

    Presents a simple way to implement the thermometric property of a semiconductor diode to produce a thermometer with a nearly linear dependence upon temperature over a wide range of temperatures. (JRH)

  2. Enhanced vbasis laser diode package

    Science.gov (United States)

    Deri, Robert J.; Chen, Diana; Bayramian, Andy; Freitas, Barry; Kotovsky, Jack

    2014-08-19

    A substrate having an upper surface and a lower surface is provided. The substrate includes a plurality of v-grooves formed in the upper surface. Each v-groove includes a first side and a second side perpendicular to the first side. A laser diode bar assembly is disposed within each of the v-grooves and attached to the first side. The laser diode bar assembly includes a first adhesion layer disposed on the first side of the v-groove, a metal plate attached to the first adhesion layer, a second adhesion layer disposed over the metal plate, and a laser diode bar attached to the second adhesion layer. The laser diode bar has a coefficient of thermal expansion (CTE) substantially similar to that of the metal plate.

  3. Studies of cold protection diodes

    International Nuclear Information System (INIS)

    Carcagno, R.; Zeigler, J.

    1990-01-01

    The feasibility of a passive quench protection system for the Superconducting Supercollider (SSC) main ring magnets depends on the radiation resistance and reliability of the diodes used as current bypass elements. These diodes would be located inside the magnet cryostat, subjecting them to liquid helium temperature and a relatively high radiation flux. Experimental and theoretical efforts have identified a commercially available diode which appears to be capable of surviving the cryogenic temperature and radiation environment of the accelerator. High current IV measurements indicate that the usable lifetime of this diode, based on an estimate of the peak junction temperature during a quench pulse, is an order of magnitude greater then than the expected lifetime of the SSC itself. However, an unexpected relationship was discovered between the diode turn-on voltage at 5 K and the most recent reverse voltage or temperature excursion. This turn-on voltage as a function of radiation exposure appears to be erratic and indicates a need for further investigation. 14 refs., 8 figs., 2 tabs

  4. Studies of cold protection diodes

    International Nuclear Information System (INIS)

    Carcagno, R.; Zeigler, J.

    1990-03-01

    The feasibility of a passive quench protection system for the Superconducting Supercollider (SSC) main ring magnets depends on the radiation resistance and reliability of the diodes used as current bypass elements. These diodes would be located inside the magnet cryostat, subjecting them to liquid helium temperature and a relatively high radiation flux. Experimental and theoretical efforts have identified a commercially available diode which appears to be capable of surviving the cryogenic temperature and radiation environment of the accelerator. High current 4 measurements indicate that the usable lifetime of this diode, based on an estimate of the peak junction temperature during a quench pulse, is an order of magnitude greater then than the expected lifetime of the SSC itself. However, an unexpected relationship was discovered between the diode turn-on voltage at 5 K and the most recent reverse voltage or temperature excursion. This turn-on voltage as a function of radiation exposure appears to be erratic and indicates a need for further investigation. 11 refs., 8 figs., 2 tabs

  5. 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...

  6. 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...

  7. Wideband 4-diode sampling circuit

    Science.gov (United States)

    Wojtulewicz, Andrzej; Radtke, Maciej

    2016-09-01

    The objective of this work was to develop a wide-band sampling circuit. The device should have the ability to collect samples of a very fast signal applied to its input, strengthen it and prepare for further processing. The study emphasizes the method of sampling pulse shaping. The use of ultrafast pulse generator allows sampling signals with a wide frequency spectrum, reaching several gigahertzes. The device uses a pulse transformer to prepare symmetrical pulses. Their final shape is formed with the help of the step recovery diode, two coplanar strips and Schottky diode. Made device can be used in the sampling oscilloscope, as well as other measurement system.

  8. Laser diode technology and applications

    International Nuclear Information System (INIS)

    Figueroa, L.

    1989-01-01

    This book covers a wide range of semiconductor laser technology, from new laser structures and laser design to applications in communications, remote sensing, and optoelectronics. The authors report on new laser diode physics and applications and present a survey of the state of the art as well as progress in new developments

  9. 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...

  10. High power diode pumped solid state lasers

    International Nuclear Information System (INIS)

    Solarz, R.; Albrecht, G.; Beach, R.; Comaskey, B.

    1992-01-01

    Although operational for over twenty years, diode pumped solid state lasers have, for most of their existence, been limited to individual diodes pumping a tiny volume of active medium in an end pumped configuration. More recent years have witnessed the appearance of diode bars, packing around 100 diodes in a 1 cm bar which have enabled end and side pumped small solid state lasers at the few Watt level of output. This paper describes the subsequent development of how proper cooling and stacking of bars enables the fabrication of multi kill average power diode pump arrays with irradiances of 1 kw/cm peak and 250 W/cm 2 average pump power. Since typical conversion efficiencies from the diode light to the pumped laser output light are of order 30% or more, kW average power diode pumped solid state lasers now are possible

  11. 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.

  12. A single-molecule diode

    Science.gov (United States)

    Elbing, Mark; Ochs, Rolf; Koentopp, Max; Fischer, Matthias; von Hänisch, Carsten; Weigend, Florian; Evers, Ferdinand; Weber, Heiko B.; Mayor, Marcel

    2005-01-01

    We have designed and synthesized a molecular rod that consists of two weakly coupled electronic π -systems with mutually shifted energy levels. The asymmetry thus implied manifests itself in a current–voltage characteristic with pronounced dependence on the sign of the bias voltage, which makes the molecule a prototype for a molecular diode. The individual molecules were immobilized by sulfur–gold bonds between both electrodes of a mechanically controlled break junction, and their electronic transport properties have been investigated. The results indeed show diode-like current–voltage characteristics. In contrast to that, control experiments with symmetric molecular rods consisting of two identical π -systems did not show significant asymmetries in the transport properties. To investigate the underlying transport mechanism, phenomenological arguments are combined with calculations based on density functional theory. The theoretical analysis suggests that the bias dependence of the polarizability of the molecule feeds back into the current leading to an asymmetric shape of the current–voltage characteristics, similar to the phenomena in a semiconductor diode. PMID:15956208

  13. Molecular diodes in optical rectennas

    Science.gov (United States)

    Duché, David; Palanchoke, Ujwol; Terracciano, Luigi; Dang, Florian-Xuan; Patrone, Lionel; Le Rouzo, Judikael; Balaban, Téodore Silviu; Alfonso, Claude; Charai, Ahmed; Margeat, Olivier; Ackermann, Jorg; Gourgon, Cécile; Simon, Jean-Jacques; Escoubas, Ludovic

    2016-09-01

    The photo conversion efficiencies of the 1st and 2nd generat ion photovoltaic solar cells are limited by the physical phenomena involved during the photo-conversion processes. An upper limit around 30% has been predicted for a monojunction silicon solar cell. In this work, we study 3rd generation solar cells named rectenna which could direct ly convert visible and infrared light into DC current. The rectenna technology is at odds with the actual photovoltaic technologies, since it is not based on the use of semi-conducting materials. We study a rectenna architecture consist ing of plasmonic nano-antennas associated with rectifying self assembled molecular diodes. We first opt imized the geometry of plasmonic nano-antennas using an FDTD method. The optimal antennas are then realized using a nano-imprint process and associated with self assembled molecular diodes in 11- ferrocenyl-undecanethiol. Finally, The I(V) characterist ics in darkness of the rectennas has been carried out using an STM. The molecular diodes exhibit averaged rect ification ratios of 5.

  14. Electron injection in diodes with field emission

    International Nuclear Information System (INIS)

    Denavit, J.; Strobel, G.L.

    1986-01-01

    This paper presents self-consistent steady-state solutions of the space charge, transmitted current, and return currents in diodes with electron injection from the cathode and unlimited field emission of electrons and ions from both electrodes. Time-dependent particle simulations of the diode operation confirm the analytical results and show how these steady states are reached. The results are applicable to thermionic diodes and to photodiodes

  15. 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 ...

  16. Thermometric characteristics of silicon semiconductor diodes

    International Nuclear Information System (INIS)

    Bezverkhnyaya, N.S.; Vasil'ev, L.M.; Dmitrevskij, Yu.P.; Mel'nik, Yu.M.

    1975-01-01

    To substantiate the feasibility of using silicon diodes made by the Soviet industry as detectors of temperature in the 15 - 300 K range, 25 different types of silicon diodes have been investigated. The results obtained for the thermometric characteristics of the diodes are presented in tabular form. It is shown that a stability of readings of up to 0.05 deg can be obtained [ru

  17. Laser diode technology for coherent communications

    Science.gov (United States)

    Channin, D. J.; Palfrey, S. L.; Toda, M.

    1989-01-01

    The effect of diode laser characteristics on the overall performance capabilities of coherent communication systems is discussed. In particular, attention is given to optical performance issues for diode lasers in coherent systems, measurements of key performance parameters, and optical requirements for coherent single-channel and multichannel communication systems. The discussion also covers limitations imposed by diode laser optical performance on multichannel system capabilities and implications for future developments.

  18. Thermic diode performance characteristics and design manual

    Science.gov (United States)

    Bernard, D. E.; Buckley, S.

    1979-01-01

    Thermic diode solar panels are a passive method of space and hot water heating using the thermosyphon principle. Simplified methods of sizing and performing economic analyses of solar heating systems had until now been limited to passive systems. A mathematical model of the thermic diode including its high level of stratification has been constructed allowing its performance characteristics to be studied. Further analysis resulted in a thermic diode design manual based on the f-chart method.

  19. Focusing experiments with light ion diodes

    International Nuclear Information System (INIS)

    Johnson, D.L.

    1978-01-01

    A review of recent experimental and theoretical work at Sandia Laboratories on magnetically insulated single stage ion diodes for inertial confinement fusion experiments is presented. The production, focusing, and numerical simulation of a 0.5 TW annular proton beam using the Proto I dual transmission line generator is described. The modular magnetically insulated ion diode for the Hydra generator is also described along with recent experimental results. A brief description of how an array of modular diodes similar to the Hydra magnetically insulated diode could be used on the EBFA I generator for breakeven fusion experiments is presented

  20. Progress in semiconductor laser diodes: SPIE volume 723

    International Nuclear Information System (INIS)

    Eichen, E.

    1987-01-01

    This book contains proceedings arranged under the following session headings: High power diode lasers; single emitters and arrays; Ultrahigh speed modulation of semiconductor diode lasers; Coherence and linewidth stabilized semiconductor lasers; and Growth, fabrication, and evaluation of laser diodes

  1. 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.

  2. outcome of diode laser cyclophotocoagulation in neovascular ...

    African Journals Online (AJOL)

    Duke

    including, ruby, ND:YAG, argon, krypton and, more recently, trans scleral cyclophotocoagulation with the diode laser, which has been shown to be more effective with less side effects than the others. The diode laser, 810nm, has. 4,5 greater melanin absorption compared to other lasers. Of the various cyclodestructive laser ...

  3. Graphene geometric diodes for terahertz rectennas

    International Nuclear Information System (INIS)

    Zhu Zixu; Joshi, Saumil; Grover, Sachit; Moddel, Garret

    2013-01-01

    We demonstrate a new thin-film graphene diode called a geometric diode that relies on geometric asymmetry to provide rectification at 28 THz. The geometric diode is coupled to an optical antenna to form a rectenna that rectifies incoming radiation. This is the first reported graphene-based antenna-coupled diode working at 28 THz, and potentially at optical frequencies. The planar structure of the geometric diode provides a low RC time constant, on the order of 10 −15 s, required for operation at optical frequencies, and a low impedance for efficient power transfer from the antenna. Fabricated geometric diodes show asymmetric current–voltage characteristics consistent with Monte Carlo simulations for the devices. Rectennas employing the geometric diode coupled to metal and graphene antennas rectify 10.6 µm radiation, corresponding to an operating frequency of 28 THz. The graphene bowtie antenna is the first demonstrated functional antenna made using graphene. Its response indicates that graphene is a suitable terahertz resonator material. Applications for this terahertz diode include terahertz-wave and optical detection, ultra-high-speed electronics and optical power conversion. (paper)

  4. Electromagnetic wave analogue of an electronic diode

    International Nuclear Information System (INIS)

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

    2011-01-01

    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 rotation of the polarization state and is also a key component in 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 extraordinarily strong nonlinear wave propagation effect in the same way as the electronic diode function is provided by the 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 differs by a factor of 65.

  5. Laser diode package with enhanced cooling

    Science.gov (United States)

    Deri, Robert J [Pleasanton, CA; Kotovsky, Jack [Oakland, CA; Spadaccini, Christopher M [Oakland, CA

    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.

  6. Carbon nanotube Schottky diode: an atomic perspective

    International Nuclear Information System (INIS)

    Bai, P; Li, E; Kurniawan, O; Koh, W S; Lam, K T

    2008-01-01

    The electron transport properties of semiconducting carbon nanotube (SCNT) Schottky diodes are investigated with atomic models using density functional theory and the non-equilibrium Green's function method. We model the SCNT Schottky diode as a SCNT embedded in the metal electrode, which resembles the experimental set-up. Our study reveals that the rectification behaviour of the diode is mainly due to the asymmetric electron transmission function distribution in the conduction and valence bands and can be improved by changing metal-SCNT contact geometries. The threshold voltage of the diode depends on the electron Schottky barrier height which can be tuned by altering the diameter of the SCNT. Contrary to the traditional perception, the metal-SCNT contact region exhibits better conductivity than the other parts of the diode

  7. Tunable diode-pumped-LNA laser

    International Nuclear Information System (INIS)

    Cassimi, A.; Hardy, V.; Hamel, J.; Leduc, M.

    1987-01-01

    Diode-pumped crystals provided recently new compact laser devices. We report the first end pumping of a La x Nd 1-x MgAl 11 O 19 (LNA) crystal using a 200mW diode array (Spectra Diode Lab). We also report the first results obtained with a 1mW diode (SONY). This C.W. laser can be tuned from 1.048μm to 1.086μm. Without selective elements in the cavity, the laser emits around 1.054μm with a threshold of 24mW and a slope efficiency of 4.4% (output mirror of transmission T = 1%) when pumped by the diode array. With the selective elements, the threshold increases to 100mW and we obtain a power of 4mW for a pump power of 200mW

  8. Stopping atoms with diode lasers

    International Nuclear Information System (INIS)

    Watts, R.N.; Wieman, C.E.

    1986-01-01

    The use of light pressure to cool and stop neutral atoms has been an area of considerable interest recently. Cooled neutral atoms are needed for a variety of interesting experiments involving neutral atom traps and ultrahigh-resolution spectroscopy. Laser cooling of sodium has previously been demonstrated using elegant but quite elaborate apparatus. These techniques employed stabilized dye lasers and a variety of additional sophisticated hardware. The authors have demonstrated that a frequency chirp technique can be implemented using inexpensive diode lasers and simple electronics. In this technique the atoms in an atomic beam scatter resonant photons from a counterpropagating laser beam. The momentum transfer from the photons slows the atoms. The primary difficulty is that as the atoms slow their Doppler shift changes, and so they are no longer in resonance with the incident photons. In the frequency chirp technique this is solved by rapidly changing the laser frequency so that the atoms remain in resonance. To achieve the necessary frequency sweep with a dye laser one must use an extremely sophisticated high-speed electrooptic modulator. With a diode laser, however, the frequency can be smoothly and rapidly varied over many gigahertz simply by changing the injection current

  9. Spectroscopic amplifier for pin diode

    International Nuclear Information System (INIS)

    Alonso M, M. S.; Hernandez D, V. M.; Vega C, H. R.

    2014-10-01

    The photodiode remains the basic choice for the photo-detection and is widely used in optical communications, medical diagnostics and field of corpuscular radiation. In detecting radiation it has been used for monitoring radon and its progeny and inexpensive spectrometric systems. The development of a spectroscopic amplifier for Pin diode is presented which has the following characteristics: canceler Pole-Zero (P/Z) with a time constant of 8 μs; constant gain of 57, suitable for the acquisition system; 4th integrator Gaussian order to waveform change of exponential input to semi-Gaussian output and finally a stage of baseline restorer which prevents Dc signal contribution to the next stage. The operational amplifier used is the TLE2074 of BiFET technology of Texas Instruments with 10 MHz bandwidth, 25 V/μs of slew rate and a noise floor of 17 nv/(Hz)1/2. The integrated circuit has 4 operational amplifiers and in is contained the total of spectroscopic amplifier that is the goal of electronic design. The results show like the exponential input signal is converted to semi-Gaussian, modifying only the amplitude according to the specifications in the design. The total system is formed by the detector, which is the Pin diode, a sensitive preamplifier to the load, the spectroscopic amplifier that is what is presented and finally a pulse height analyzer (Mca) which is where the spectrum is shown. (Author)

  10. Diode lasers: From laboratory to industry

    Science.gov (United States)

    Nasim, Hira; Jamil, Yasir

    2014-03-01

    The invention of first laser in 1960 triggered the discovery of several new families of lasers. A rich interplay of different lasing materials resulted in a far better understanding of the phenomena particularly linked with atomic and molecular spectroscopy. Diode lasers have gone through tremendous developments on the forefront of applied physics that have shown novel ways to the researchers. Some interesting attributes of the diode lasers like cost effectiveness, miniature size, high reliability and relative simplicity of use make them good candidates for utilization in various practical applications. Diode lasers are being used by a variety of professionals and in several spectroscopic techniques covering many areas of pure and applied sciences. Diode lasers have revolutionized many fields like optical communication industry, medical science, trace gas monitoring, studies related to biology, analytical chemistry including elemental analysis, war fare studies etc. In this paper the diode laser based technologies and measurement techniques ranging from laboratory research to automated field and industry have been reviewed. The application specific developments of diode lasers and various methods of their utilization particularly during the last decade are discussed comprehensively. A detailed snapshot of the current state of the art diode laser applications is given along with a detailed discussion on the upcoming challenges.

  11. A single-molecule diode

    Science.gov (United States)

    Elbing, Mark; Ochs, Rolf; Koentopp, Max; Fischer, Matthias; von Hänisch, Carsten; Weigend, Florian; Evers, Ferdinand; Weber, Heiko B.; Mayor, Marcel

    2005-06-01

    We have designed and synthesized a molecular rod that consists of two weakly coupled electronic π -systems with mutually shifted energy levels. The asymmetry thus implied manifests itself in a current-voltage characteristic with pronounced dependence on the sign of the bias voltage, which makes the molecule a prototype for a molecular diode. The individual molecules were immobilized by sulfur-gold bonds between both electrodes of a mechanically controlled break junction, and their electronic transport properties have been investigated. The results indeed show diode-like current-voltage characteristics. In contrast to that, control experiments with symmetric molecular rods consisting of two identical π -systems did not show significant asymmetries in the transport properties. To investigate the underlying transport mechanism, phenomenological arguments are combined with calculations based on density functional theory. The theoretical analysis suggests that the bias dependence of the polarizability of the molecule feeds back into the current leading to an asymmetric shape of the current-voltage characteristics, similar to the phenomena in a semiconductor diode. Author contributions: F.E., H.B.W., and M.M. designed research; M.E., R.O., M.K., M.F., F.E., H.B.W., and M.M. performed research; M.E., R.O., M.K., M.F., C.v.H., F.W., F.E., H.B.W., and M.M. contributed new reagents/analytic tools; M.E., R.O., M.K., C.v.H., F.E., H.B.W., and M.M. analyzed data; and F.E., H.B.W., and M.M. wrote the paper.This paper was submitted directly (Track II) to the PNAS office.Abbreviations: A, acceptor; D, donor; MCB, mechanically controlled break junction.Data deposition: The atomic coordinates have been deposited in the Cambridge Structural Database, Cambridge Crystallographic Data Centre, Cambridge CB2 1EZ, United Kingdom (CSD reference no. 241632).

  12. Cold cathode diode X-ray source

    International Nuclear Information System (INIS)

    Cooperstein, G.; Lanza, R.C.; Sohval, A.R.

    1983-01-01

    A cold cathode diode X-ray source for radiation imaging, especially computed tomography, comprises a rod-like anode and a generally cylindrical cathode, concentric with the anode. The spacing between anode and cathode is so chosen that the diode has an impedance in excess of 100 ohms. The anode may be of tungsten, or of carbon with a tungsten and carbon coating. An array of such diodes may be used with a closely packed array of detectors to produce images of rapidly moving body organs, such as the beating heart. (author)

  13. Cern DD4424 ROM Diode Matrix

    CERN Multimedia

    A diode matrix is an extremely low-density form of read-only memory. It's one of the earliest forms of ROMs (dating back to the 1950s). Each bit in the ROM is represented by the presence or absence of one diode. The ROM is easily user-writable using a soldering iron and pair of wire cutters.This diode matrix board is a floppy disk boot ROM for a PDP-11, and consists of 32 16-bit words. When you access an address on the ROM, the circuit returns the represented data from that address.

  14. A Diode Matrix model M792

    CERN Multimedia

    A diode matrix is an extremely low-density form of read-only memory. It's one of the earliest forms of ROMs (dating back to the 1950s). Each bit in the ROM is represented by the presence or absence of one diode. The ROM is easily user-writable using a soldering iron and pair of wire cutters.This diode matrix board is a floppy disk boot ROM for a PDP-11, and consists of 32 16-bit words. When you access an address on the ROM, the circuit returns the represented data from that address.

  15. A Portable Diode Array Spectrophotometer.

    Science.gov (United States)

    Stephenson, David

    2016-05-01

    A cheap portable visible light spectrometer is presented. The spectrometer uses readily sourced items and could be constructed by anyone with a knowledge of electronics. The spectrometer covers the wavelength range 450-725 nm with a resolution better than 5 nm. The spectrometer uses a diffraction grating to separate wavelengths, which are detected using a 128-element diode array, the output of which is analyzed using a microprocessor. The spectrum is displayed on a small liquid crystal display screen and can be saved to a micro SD card for later analysis. Battery life (2 × AAA) is estimated to be 200 hours. The overall dimensions of the unit are 120 × 65 × 60 mm, and it weighs about 200 g. © The Author(s) 2016.

  16. Semiconductor laser diodes and the design of a D.C. powered laser diode drive unit

    OpenAIRE

    Cappuccio, Joseph C., Jr.

    1988-01-01

    Approved for public release; distribution is unlimited This thesis addresses the design, development and operational analysis of a D.C. powered semiconductor laser diode drive unit. A laser diode requires an extremely stable power supply since a picosecond spike of current or power supply switching transient could result in permanent damage. The design offers stability and various features for operational protection of the laser diode. The ability to intensity modulate (analog) and pulse m...

  17. Arbitrary waveform generator to improve laser diode driver performance

    Science.gov (United States)

    Fulkerson, Jr, Edward Steven

    2015-11-03

    An arbitrary waveform generator modifies the input signal to a laser diode driver circuit in order to reduce the overshoot/undershoot and provide a "flat-top" signal to the laser diode driver circuit. The input signal is modified based on the original received signal and the feedback from the laser diode by measuring the actual current flowing in the laser diode after the original signal is applied to the laser diode.

  18. Investigation of MIM Diodes for RF Applications

    KAUST Repository

    Khan, Adnan

    2015-01-01

    zero bias condition as well as the possibility of realizing them through printing makes them attractive for (Radio Frequency) RF applications. However, MIM diodes have not been explored much for RF applications. One reason preventing their widespread RF

  19. Compact laser-diode-based femtosecond sources

    International Nuclear Information System (INIS)

    Brown, C T A; Cataluna, M A; Lagatsky, A A; Rafailov, E U; Agate, M B; Leburn, C G; Sibbett, W

    2004-01-01

    This paper describes the development of compact femtosecond laser systems that are capable of being directly pumped by laser diodes or are based directly on laser diodes. The paper demonstrates the latest results in a highly efficient vibronic based gain medium and a diode-pumped Yb:KYW laser is reported that has a wall plug efficiency >14%. A Cr 4+ :YAG oscillator is described that generates transform-limited pulses of 81 fs duration at a pulse repetition frequency of >4 GHz. The development of Cr 3+ :LiSAF lasers that can be operated using power supplies based on batteries is briefly discussed. We also present a summary of work being carried out on the generation of fs-pulses from laser diodes and discuss the important issues in this area. Finally, we outline results obtained on the generation of pulses as short as 550 fs directly from a two-section quantum dot laser without any external pulse compression

  20. 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.

  1. Developments in lead-salt diode lasers

    International Nuclear Information System (INIS)

    Partin, D.L.

    1985-01-01

    Lead-chalcogenide diode lasers are useful as mid-infrared sources (2-1/2 <λ<30 μm), but have generally operated CW below 100K. A new materials system, PbEuSeTe, has been used to fabricate diode lasers operating from 10K (at 6.5 μm wavelength) up to 174K CW (at 4.4 μm) and up to 280K pulsed (at 3.8 μm). These are large optical cavity single quantum well devices grown by molecular beam epitaxy. These are currently the highest diode laser operating temperatures ever achieved at these wavelengths to our knowledge. Single ended output powers as high as 1 mW single mode (5 mW multimode) have been attained from mesa stripe diodes. These characteristics make these devices attractive for long wavelength fiber optic sensor/communications systems. The performance limits of these devices are discussed

  2. AASERT-97 Development of New Diode Lasers

    National Research Council Canada - National Science Library

    Peyghambarian, Nasser

    2001-01-01

    This research explored new ways for diode laser fabrications. Focused was on the development of efficient organic light emitting materials and the fabrication of laser structures incorporating these materials...

  3. Application of PIN diodes in Physics Research

    International Nuclear Information System (INIS)

    Ramirez-Jimenez, F. J.; Mondragon-Contreras, L.; Cruz-Estrada, P.

    2006-01-01

    A review of the application of PIN diodes as radiation detectors in different fields of Physics research is presented. The development and research in semiconductor technology, the use of PIN diodes in particle counting, X-and γ-ray spectroscopy, medical applications and charged particle spectroscopy are considered. Emphasis is made in the activities realized in the different research and development Mexican institutions dealing with this kind of radiation detectors

  4. Phase-change radiative thermal diode

    OpenAIRE

    Ben-Abdallah, Philippe; Biehs, Svend-Age

    2013-01-01

    A thermal diode transports heat mainly in one preferential direction rather than in the opposite direction. This behavior is generally due to the non-linear dependence of certain physical properties with respect to the temperature. Here we introduce a radiative thermal diode which rectifies heat transport thanks to the phase transitions of materials. Rectification coefficients greater than 70% and up to 90% are shown, even for small temperature differences. This result could have important ap...

  5. Diode lasers and their applications in spectrometry

    International Nuclear Information System (INIS)

    Pavone, F.S.

    1997-01-01

    The impact of semiconductor diode laser in different fields ranging from communications to spectroscopy is becoming huge and pushes the research into developing sources satisfying the different requirements. For applications related to trace gas detection, the low amplitude noise in the light source of semiconductor diode laser is sufficient to obtain interesting results. Trace gas of molecular species as methane is interesting for different reason: it plays an important role in both radiative transport an photochemistry in the atmosphere

  6. Laser semiconductor diode integrated with frequency doubler

    International Nuclear Information System (INIS)

    Tighineanu, I.; Dorogan, V.; Suruceanu, G.

    2003-01-01

    The invention relates to the technology of optoelectronic semiconductor devices and may be used in the production of laser semiconductor diodes integrated with optical nonlinear elements. The laser semiconductor diode integrated with frequency doubler includes a semiconductor substrate, a laser structure with waveguide. metal contacts in the waveguide of the laser structure it is formed a nanostructured field so that the nanostructure provides for the fulfillment of the phase synchronism conditions

  7. Radiation effects in semiconductor laser diode arrays

    International Nuclear Information System (INIS)

    Carson, R.F.

    1988-01-01

    The effects of radiation events are important for many of the present and future applications that involve optoelectronic components. Laser diodes show a strong resistance to degradation by gamma rays, prompt x-rays and (to a lesser extent), neutrons. This is due to the short carrier lifetime that is associated with stimulated emission and the high current injection conditions that are present in these devices. Radiation-resistant properties should carry over to many of the more recently developed devices such as multi-stripe array and broad area laser diodes. There are, however, additional considerations for radiation tolerance that are introduced by these devices. Arrays and other high power laser diodes have larger active region volumes than lower power single stripe devices. In addition, evanescent field coupling between stripes, the material quality available from newer MOCVD epitaxial growth techniques, and stripe definition methods may all influence the radiation tolerance of the high power laser diode devices. Radiation tests have been conducted on various GaAs-GaAlAs laser diode array and broad area devices. Tests involving total gamma dose have indicated that high power laser diodes and arrays have small degradations in light power output with current input after 4 MRad(Si) of radiation from a Co 60 source. Additional test results involving flash x-rays indicate that high power diode lasers and arrays are tolerant to 10 12 rads(Si)/sec, when observed on microsecond or millisecond time scales. High power diode laser devices were also irradiated with neutrons to a fluence of 10 14 neutrons/cm 2 with some degradation of threshold current level

  8. Performance of the cold powered diodes and diode leads in the main magnets of the LHC

    CERN Document Server

    Willering, G P; Bajko, M; Bednarek, M; Bottura, L; Charifoulline, Z; Dahlerup-Petersen, K; Dib, G; D'Angelo, G; Gharib, A; Grand-Clement, L; Izquierdo Bermudez, S; Prin, H; Roger, V; Rowan, S; Savary, F; Tock, J-Ph; Verweij, A

    2015-01-01

    During quench tests in 2011 variations in resistance of an order of magnitude were found in the diode by-pass circuit of the main LHC magnets. An investigation campaign was started to understand the source, the occurrence and the impact of the high resistances. Many tests were performed offline in the SM18 test facility with a focus on the contact resistance of the diode to heat sink contact and the diode wafer temperature. In 2014 the performance of the diodes and diode leads of the main dipole bypass systems in the LHC was assessed during a high current qualification test. In the test a current cycle similar to a magnet circuit discharge from 11 kA with a time constant of 100 s was performed. Resistances of up to 600 μΩ have been found in the diode leads at intermediate current, but in general the high resistances decrease at higher current levels and no sign of overheating of diodes has been seen and the bypass circuit passed the test. In this report the performance of the diodes and in particular the co...

  9. Operation and maintenance manual for diode performance analysis program DIODE0

    International Nuclear Information System (INIS)

    Boyer, W.B.

    1977-03-01

    This program computes diode performance parameters for the e beam fusion accelerators HYDRA, PROTO I and PROTO II. The program works in conjunction with other programs in the data acquisition facility library. It reads the input data produced by the Tekronix R7012 Transient Digitizers off the disc. It then computes and plots the diode corrected voltages, impedances, powers, and energies

  10. Next generation diode lasers with enhanced brightness

    Science.gov (United States)

    Ried, S.; Rauch, S.; Irmler, L.; Rikels, J.; Killi, A.; Papastathopoulos, E.; Sarailou, E.; Zimer, H.

    2018-02-01

    High-power diode lasers are nowadays well established manufacturing tools in high power materials processing, mainly for tactile welding, surface treatment and cladding applications. Typical beam parameter products (BPP) of such lasers range from 30 to 50 mm·mrad at several kilowatts of output power. TRUMPF offers a product line of diode lasers to its customers ranging from 150 W up to 6 kW of output power. These diode lasers combine high reliability with small footprint and high efficiency. However, up to now these lasers are limited in brightness due to the commonly used spatial and coarse spectral beam combining techniques. Recently diode lasers with enhanced brightness have been presented by use of dense wavelength multiplexing (DWM). In this paper we report on TRUMPF's diode lasers utilizing DWM. We demonstrate a 2 kW and a 4 kW system ideally suited for fine welding and scanner welding applications. The typical laser efficiency is in the range of 50%. The system offers plug and play exchange of the fiber beam delivery cable, multiple optical outputs and integrated cooling in a very compact package. An advanced control system offers flexible integration in any customer's shop floor environment and includes industry 4.0 capabilities (e.g. condition monitoring and predictive maintenance).

  11. Suitability of integrated protection diodes from diverse semiconductor technologies

    NARCIS (Netherlands)

    van Wanum, Maurice; Lebouille, Tom; Visser, Guido; van Vliet, Frank Edward

    2009-01-01

    Abstract In this article diodes from three different semiconductor technologies are compared based on their suitability to protect a receiver. The semiconductor materials involved are silicon, gallium arsenide and gallium nitride. The diodes in the diverse semiconductor technologies themselves are

  12. High efficiency and broadband acoustic diodes

    Science.gov (United States)

    Fu, Congyi; Wang, Bohan; Zhao, Tianfei; Chen, C. Q.

    2018-01-01

    Energy transmission efficiency and working bandwidth are the two major factors limiting the application of current acoustic diodes (ADs). This letter presents a design of high efficiency and broadband acoustic diodes composed of a nonlinear frequency converter and a linear wave filter. The converter consists of two masses connected by a bilinear spring with asymmetric tension and compression stiffness. The wave filter is a linear mass-spring lattice (sonic crystal). Both numerical simulation and experiment show that the energy transmission efficiency of the acoustic diode can be improved by as much as two orders of magnitude, reaching about 61%. Moreover, the primary working band width of the AD is about two times of the cut-off frequency of the sonic crystal filter. The cut-off frequency dependent working band of the AD implies that the developed AD can be scaled up or down from macro-scale to micro- and nano-scale.

  13. Self-magnetically insulated ion diode

    International Nuclear Information System (INIS)

    VanDevender, J.; Quintenz, J.; Leeper, R.; Johnson, D.; Crow, J.

    1981-01-01

    Light ion diodes for producing 1--100 TW ion beams are required for inertial confinement fusion. The theory, numerical simulations, and experiments on a self-magnetically insulated ion diode are presented. The treatment is from the point of view of a self-magnetically insulated transmission line with an ion loss current and differs from the usual treatment of the pinched electron beam diode. The simulations show that the ratio V/IZ 0 =0.25 in such a structure with voltage V, local total current I, and local vacuum wave impedance Z 0 . The ion current density is enhanced by a factor of approximately 2 over the simple space-charge limited value. The simulation results are verified in an experiment. An analytical theory is then presented for scaling the results to produce a focused beam of protons with a power of up to 10 13 W

  14. Thermal diode made by nematic liquid crystal

    Energy Technology Data Exchange (ETDEWEB)

    Melo, Djair, E-mail: djfmelo@gmail.com [Instituto de Física, Universidade Federal de Alagoas, Av. Lourival Melo Mota, s/n, 57072-900 Maceió, AL (Brazil); Fernandes, Ivna [Instituto de Física, Universidade Federal de Alagoas, Av. Lourival Melo Mota, s/n, 57072-900 Maceió, AL (Brazil); Moraes, Fernando [Departamento de Física, CCEN, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-900, João Pessoa, PB (Brazil); Departamento de Física, Universidade Federal Rural de Pernambuco, 52171-900 Recife, PE (Brazil); Fumeron, Sébastien [Institut Jean Lamour, Université de Lorraine, BP 239, Boulevard des Aiguillettes, 54506 Vandoeuvre les Nancy (France); Pereira, Erms [Escola Politécnica de Pernambuco, Universidade de Pernambuco, Rua Benfíca, 455, Madalena, 50720-001 Recife, PE (Brazil)

    2016-09-07

    This work investigates how a thermal diode can be designed from a nematic liquid crystal confined inside a cylindrical capillary. In the case of homeotropic anchoring, a defect structure called escaped radial disclination arises. The asymmetry of such structure causes thermal rectification rates up to 3.5% at room temperature, comparable to thermal diodes made from carbon nanotubes. Sensitivity of the system with respect to the heat power supply, the geometry of the capillary tube and the molecular anchoring angle is also discussed. - Highlights: • An escaped radial disclination as a thermal diode made by a nematic liquid crystal. • Rectifying effects comparable to those caused by carbon and boron nitride nanotubes. • Thermal rectification increasing with radius and decreasing with height of the tube. • Asymmetric BCs cause rectification from the spatial asymmetry produced by the escape. • Symmetric BCs provide rectifications smaller than those yields by asymmetric BCs.

  15. High Performance Single Nanowire Tunnel Diodes

    DEFF Research Database (Denmark)

    Wallentin, Jesper; Persson, Johan Mikael; Wagner, Jakob Birkedal

    NWs were contacted in a NW-FET setup. Electrical measurements at room temperature display typical tunnel diode behavior, with a Peak-to-Valley Current Ratio (PVCR) as high as 8.2 and a peak current density as high as 329 A/cm2. Low temperature measurements show improved PVCR of up to 27.6....... is the tunnel (Esaki) diode, which provides a low-resistance connection between junctions. We demonstrate an InP-GaAs NW axial heterostructure with tunnel diode behavior. InP and GaAs can be readily n- and p-doped, respectively, and the heterointerface is expected to have an advantageous type II band alignment...

  16. Ultrafast photoconductor detector-laser-diode transmitter

    International Nuclear Information System (INIS)

    Wang, C.L.; Davis, B.A.; Davies, T.J.; Nelson, M.A.; Thomas, M.C.; Zagarino, P.A.

    1987-01-01

    We report the results of an experiment in which we used an ultrafast, photoconductive, radiation detector to drive a fast laser-diode transmitter. When we irradiated the neutron-damaged Cr-doped GaAs detector with 17-MeV electron beams, the temporal response was measured to be less than 30 ps. The pulses from this detector modulated a fast GaAlAs laser diode to transmit the laser output through 30- and 1100-m optical fibers. Preliminary results indicate that 50- and 80-ps time resolutions, respectively, are obtainable with these fibers. We are now working to integrate the photoconductive detector and the laser diode transmitter into a single chip

  17. Ultrafast photoconductive detector-laser-diode transmitter

    International Nuclear Information System (INIS)

    Wang, C.L.; Davies, T.J.; Nelson, M.A.; Thomas, M.C.; Zagarino, P.A.; Davis, B.A.

    1987-01-01

    The authors report the results of an experiment in which they used an ultrafast, photoconductive, radiation detector to drive a fast laser-diode transmitter. When they irradiated the neutron-damaged Cr-doped Ga/As detector with 17-MeV electron beams, the temporal response of was measured to be less than 30 ps. The pulses from this detector modulated a fast GaAlAs laser diode to transmit the laser output through 30- and 1100-m optical fibers. Preliminary results indicate that 50- and 80-ps time resolutions, respectively, are obtainable with these fibers. They are now working to integrate the photoconductive detector and the laser diode transmitter into a single chip

  18. Diode laser based light sources for biomedical applications

    DEFF Research Database (Denmark)

    Müller, André; Marschall, Sebastian; Jensen, Ole Bjarlin

    2013-01-01

    Diode lasers are by far the most efficient lasers currently available. With the ever-continuing improvement in diode laser technology, this type of laser has become increasingly attractive for a wide range of biomedical applications. Compared to the characteristics of competing laser systems, diode...... imaging. This review provides an overview of the latest development of diode laser technology and systems and their use within selected biomedical applications....

  19. Laser-diode pumped Nd:YAG lasers; Laser diode reiki Nd:YAG lasear

    Energy Technology Data Exchange (ETDEWEB)

    Yuasa, H.; Akiyama, Y.; Nakayama, M. [Toshiba Corp., Tokyo (Japan)

    2000-04-01

    Laser-diode pumped Nd:YAG lasers are expected to be applied to laser processing fields such as welding, cutting, drilling, and marking due to their potential for high efficiency and compactness. We are designing and developing laser-diode pumped Nd:YAG lasers using numerical analysis simulation techniques such as ray tracing and thermal analysis. We have succeeded in achieving a laser power of more than 3 kW with 20% efficiency, which is the best ever obtained. In addition, we have developed a laser-diode pumped green laser by second harmonic generation, for precision machining on silicon wafers. (author)

  20. An all-silicon passive optical diode.

    Science.gov (United States)

    Fan, Li; Wang, Jian; Varghese, Leo T; Shen, Hao; Niu, Ben; Xuan, Yi; Weiner, Andrew M; Qi, Minghao

    2012-01-27

    A passive optical diode effect would be useful for on-chip optical information processing but has been difficult to achieve. Using a method based on optical nonlinearity, we demonstrate a forward-backward transmission ratio of up to 28 decibels within telecommunication wavelengths. Our device, which uses two silicon rings 5 micrometers in radius, is passive yet maintains optical nonreciprocity for a broad range of input power levels, and it performs equally well even if the backward input power is higher than the forward input. The silicon optical diode is ultracompact and is compatible with current complementary metal-oxide semiconductor processing.

  1. Equilibrium double layers in extended Pierce diodes

    International Nuclear Information System (INIS)

    Ciubotariu-Jassy, C.I.

    1992-01-01

    The extended Pierce diode is similar to the standard (or classical) Pierce diode, but has passive circuit elements in place of the short circuit between the electrodes. This device is important as an approximation to real bounded plasma systems. It consists of two parallel plane electrodes (an emitter located at x=0 and a collector located at x=l) and a collisionless cold electron beam travelling between them. The electrons are neutralized by a background of comoving massive ions. This situation is analysed in this paper and new equilibrium double layer (DL) plasma structures are obtained. (author) 6 refs., 3 figs

  2. Investigation of MIM Diodes for RF Applications

    KAUST Repository

    Khan, Adnan

    2015-05-01

    Metal Insulator Metal (MIM) diodes that work on fast mechanism of tunneling have been used in a number of very high frequency applications such as (Infra-Red) IR detectors and optical Rectennas for energy harvesting. Their ability to operate under zero bias condition as well as the possibility of realizing them through printing makes them attractive for (Radio Frequency) RF applications. However, MIM diodes have not been explored much for RF applications. One reason preventing their widespread RF use is the requirement of a very thin oxide layer essential for the tunneling operation that requires sophisticated nano-fabrication processes. Another issue is that the reliability and stable performance of MIM diodes is highly dependent on the surface roughness of the metallic electrodes. Finally, comprehensive RF characterization has not been performed for MIM diodes reported in the literature, particularly from the perspective of their integration with antennas as well as their rectification abilities. In this thesis, various metal deposition methods such as sputtering, electron beam evaporation, and Atomic Layer Deposition (ALD) are compared in pursuit of achieving low surface roughness. It is worth mentioning here that MIM diodes realized through ALD method have been presented for the first time in this thesis. Amorphous metal alloy have also been investigated in terms of their low surface roughness. Zinc-oxide has been investigated for its suitability as a thin dielectric layer for MIM diodes. Finally, comprehensive RF characterization of MIM diodes has been performed in two ways: 1) by standard S-parameter methods, and 2) by investigating their rectification ability under zero bias operation. It is concluded from the Atomic Force Microscopy (AFM) imaging that surface roughness as low as sub 1 nm can be achieved reliably from crystalline metals such as copper and platinum. This value is comparable to surface roughness achieved from amorphous alloys, which are non

  3. Diode and method of making the same

    Energy Technology Data Exchange (ETDEWEB)

    Dickerson, Jeramy Ray; Wierer, Jr., Jonathan; Kaplar, Robert; Allerman, Andrew A.

    2018-03-13

    A diode includes a second semiconductor layer over a first semiconductor layer. The diode further includes a third semiconductor layer over the second semiconductor layer, where the third semiconductor layer includes a first semiconductor element over the second semiconductor layer. The third semiconductor layer additionally includes a second semiconductor element over the second semiconductor layer, wherein the second semiconductor element surrounds the first semiconductor element. Further, the third semiconductor layer includes a third semiconductor element over the second semiconductor element. Furthermore, a hole concentration of the second semiconductor element is less than a hole concentration of the first semiconductor element.

  4. Polycrystalline Diamond Schottky Diodes and Their Applications.

    Science.gov (United States)

    Zhao, Ganming

    In this work, four-hot-filament CVD techniques for in situ boron doped diamond synthesis on silicon substrates were extensively studied. A novel tungsten filament shape and arrangement used to obtain large-area, uniform, boron doped polycrystalline diamond thin films. Both the experimental results and radiative heat transfer analysis showed that this technique improved the uniformity of the substrate temperature. XRD, Raman and SEM studies indicate that large area, uniform, high quality polycrystalline diamond films were obtained. Schottky diodes were fabricated by either sputter deposition of silver or thermal evaporation of aluminum or gold, on boron doped diamond thin films. High forward current density and a high forward-to-reverse current ratio were exhibited by silver on diamond Schottky diodes. Schottky barrier heights and the majority carrier concentrations of both aluminum and gold contacted diodes were determined from the C-V measurements. Furthermore, a novel theoretical C-V-f analysis of deep level boron doped diamond Schottky diodes was performed. The analytical results agree well with the experimental results. Compressive stress was found to have a large effect on the forward biased I-V characteristics of the diamond Schottky diodes, whereas the effect on the reverse biased characteristics was relatively small. The stress effect on the forward biased diamond Schottky diode was attributed to piezojunction and piezoresistance effects. The measured force sensitivity of the diode was as high as 0.75 V/N at 1 mA forward bias. This result shows that CVD diamond device has potential for mechanical transducer applications. The quantitative photoresponse characteristics of the diodes were studied in the spectral range of 300 -1050 nm. Semi-transparent gold contacts were used for better photoresponse. Quantum efficiency as high as 50% was obtained at 500 nm, when a reverse bias of over 1 volt was applied. The Schottky barrier heights between either gold or

  5. Integrated power conditioning for laser diode arrays

    International Nuclear Information System (INIS)

    Hanks, R.L.; Kirbie, H.C.; Newton, M.A.; Farhoud, M.S.

    1995-01-01

    This compact modulator has demonstated its ability to efficiently and accurately drive a laser diode array. The addition of the crowbar protection circuit is an invaluable addition to the integrated system and is capable of protecting the laser diode array against severe damage. We showed that the correlation between measured data and simulation indicates that our modulator model is valid and can be used as a tool in the design of future systems. The spectrometer measurements that we conducted underline the imprtance of current regulation to stable laser operation

  6. Cryogenic thermometry with a common diode: type BAS16

    NARCIS (Netherlands)

    Rijpma, A.P.; ter Brake, Hermanus J.M.

    2006-01-01

    Cryogenic test experiments often require a large number of temperatures to be monitored. In order to reduce cost, we investigated the feasibility of low-cost common diodes. We chose the Philips BAS16 diode in a type SOT23 package. By means of Stycast 2850FT, these diodes were glued into alumina

  7. Cryogenic thermometry with a common diode: Type BAS16

    NARCIS (Netherlands)

    Rijpma, A.P.; Brake, ter H.J.M.

    2006-01-01

    Cryogenic test expts. often require a large no. of temps. to be monitored. In order to reduce cost, we investigated the feasibility of low-cost common diodes. We chose the Philips BAS16 diode in a type SOT23 package. By means of Stycast 2850FT, these diodes were glued into alumina holders. In total,

  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. High power diode lasers converted to the visible

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Hansen, Anders Kragh; Andersen, Peter E.

    2017-01-01

    High power diode lasers have in recent years become available in many wavelength regions. However, some spectral regions are not well covered. In particular, the visible spectral range is lacking high power diode lasers with good spatial quality. In this paper, we highlight some of our recent...... results in nonlinear frequency conversion of high power near infrared diode lasers to the visible spectral region....

  10. Experimental observations on long pulse intense ion diode operation

    International Nuclear Information System (INIS)

    Prono, D.S.; Clark, R.; Prestwich, K.

    1976-01-01

    An experiment in which a long pulse electron beam diode is converted to a reflex ion diode is reported. The results further substantiate the model of reflex ion diode behavior as well as extend the duration of ion mode operation to greater than 500 nsec

  11. Final report for EDI energy conservation with diode light; Slutrapport for EDI energibesparelser med diodelys

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    The aim of this project has been to develop technological knowledge and a competence platform for utilization of new light emitting diode technology for general lighting purposes. Furthermore the project has aimed at developing a 3 W light diode bulb to replace 15-20 W filament bulbs and halogen spotlights, and thereby demonstrating a large energy conservation potential in the use of LED technology for lighting purposes. (BA)

  12. Conical pinched electron beam diode for intense ion beam source

    International Nuclear Information System (INIS)

    Matsukawa, Yoshinobu; Nakagawa, Yoshiro

    1982-01-01

    For the purpose of improvement of the pinched electron beam diode, the production of an ion beam by a diode with electrodes in a conical shape was studied at low voltage operation (--200 kV). The ion beam is emitted from a small region of the diode apex. The mean ion beam current density near the axis at 12 cm from the diode apex is two or three times that from an usual flat parallel diode with the same dimension and impedance. The brightness and the power brightness at the otigin are 450 MA/cm 2 sr and 0.12 TW/cm 2 sr respectively. (author)

  13. Ion current reduction in pinched electron beam diodes

    International Nuclear Information System (INIS)

    Quintenz, J.P.; Poukey, J.W.

    1977-01-01

    A new version of a particle-in-cell diode code has been written which permits the accurate treatment of higher-current diodes with greater physical dimensions. Using this code, we have studied ways to reduce the ion current in large-aspect-ratio pinched electron beam diodes. In particular, we find that allowing the ions to reflex in such diodes lowers the ion to electron current ratio considerably. In a 3-MV R/d=24 case this ratio was lowered by a factor of 6--8 compared with the corresponding nonreflexing-ion diode, while still producing a superpinched electron beam

  14. Manufacture of axially insulated large-area diodes

    International Nuclear Information System (INIS)

    Ma Weiyi; Zhou Kungang; Wang Youtian; Zhang Dong; Shan Yusheng; Wang Naiyan

    1999-01-01

    The author describes the design and construction of the axially insulated large-area diodes used in the 'Heaven-1'. The four axially insulated large-area diodes are connected to the 10 ohm pulse transmission lines via the vacuum feed through tubes. The experimental results with the diodes are given. The diodes can steadily work at the voltage of 650 kV, and the diode current density is about 80 A per cm 2 with a pulse width of 220 ns. The electron beams with a total energy of 25 kJ are obtained

  15. Spin-current diode with a ferromagnetic semiconductor

    International Nuclear Information System (INIS)

    Sun, Qing-Feng; Xie, X. C.

    2015-01-01

    Diode is a key device in electronics: the charge current can flow through the device under a forward bias, while almost no current flows under a reverse bias. Here, we propose a corresponding device in spintronics: the spin-current diode, in which the forward spin current is large but the reversed one is negligible. We show that the lead/ferromagnetic quantum dot/lead system and the lead/ferromagnetic semiconductor/lead junction can work as spin-current diodes. The spin-current diode, a low dissipation device, may have important applications in spintronics, as the conventional charge-current diode does in electronics

  16. Highly efficient silicon light emitting diode

    NARCIS (Netherlands)

    Le Minh, P.; Holleman, J.; Wallinga, Hans

    2002-01-01

    In this paper, we describe the fabrication, using standard silicon processing techniques, of silicon light-emitting diodes (LED) that efficiently emit photons with energy around the silicon bandgap. The improved efficiency had been explained by the spatial confinement of charge carriers due to a

  17. Proto-I switching and diode studies

    International Nuclear Information System (INIS)

    Prestwich, K.R.; Miller, P.A.; McDaniel, D.H.; Poukey, J.W.; Widner, M.M.; Goldstein, S.A.

    1975-01-01

    Proto-I is a 3 MV, 800 kA, 24 ns electron beam accelerator that is under development at Sandia Laboratories. It represents an initial effort to develop a scalable technology that is applicable to accelerators for electron beam driven, inertial confinement fusion studies. Energy is supplied to each of the two diodes from six oil-dielectric Blumlein transmission lines (PFL) operating in parallel. A Marx generator charges three intermediate storage, water-dielectric capacitors which subsequently transfer the stored energy to the PFL. The discharge of the PFL is initiated by the simultaneous closure of 12 triggered oil-dielectric rail switches. Data will be presented on the operation of these multichannel switches. The two diodes have a common anode. Cathode diameters can be varied from 10 to 60 cm. Results of initial diode experiments and comparisons with theory are discussed. Plasma filled diode experiments are also reported, indicating pinch collapse velocities in excess of 10 9 cm/s

  18. The Fuge Tube Diode Array Spectrophotometer

    Science.gov (United States)

    Arneson, B. T.; Long, S. R.; Stewart, K. K.; Lagowski, J. J.

    2008-01-01

    We present the details for adapting a diode array UV-vis spectrophotometer to incorporate the use of polypropylene microcentrifuge tubes--fuge tubes--as cuvettes. Optical data are presented validating that the polyethylene fuge tubes are equivalent to the standard square cross section polystyrene or glass cuvettes generally used in…

  19. Tunnel Diode Discriminator with Fixed Dead Time

    DEFF Research Database (Denmark)

    Diamond, J. M.

    1965-01-01

    A solid state discriminator for the range 0.4 to 10 V is described. Tunnel diodes are used for the discriminator element and in a special fixed dead time circuit. An analysis of temperature stability is presented. The regulated power supplies are described, including a special negative resistance...

  20. Entangled Light Emission From a Diode

    International Nuclear Information System (INIS)

    Stevenson, R. M.; Shields, A. J.; Salter, C. L.; Farrer, I.; Nicoll, C. A.; Ritchie, D. A.

    2011-01-01

    Electrically-driven entangled photon generation is demonstrated for the first time using a single semiconductor quantum dot embedded in a light emitting diode structure. The entanglement fidelity is shown to be of sufficient quality for applications such as quantum key distribution.

  1. 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.

  2. Diode for providing X-rays

    International Nuclear Information System (INIS)

    Rix, W.H.; Shannon, J.P.

    1991-01-01

    This patent describes a diode for generating X-rays and adapted for connection to a source of high electrical energy having a source of high energy electrons and a ground, the diode having a first end from which the X-rays are emitted, a second end and an axis extending between the ends. It comprises: a ring cathode connected to the electron source; an intermediate anode spaced from the ring cathode and with at least a portion of the intermediate anode being disposed between the ring cathode and the diode first end, the intermediate anode hiving means for decelerating electrons to cause the generation of X-rays emitted from the first end; an intermediate cathode disposed radially outwardly of the intermediate anode and connected thereto; and an inverse anode spaced from the intermediate cathode, the inverse and anode being disposed radially outwardly of the intermediate cathode and the inverse anode being positioned between the intermediate cathode and the diode second end

  3. Fluorescence lifetime imaging using light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, Gordon T; Munro, Ian; Poher, Vincent; French, Paul M W; Neil, Mark A A [Blackett Laboratory, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Elson, Daniel S [Institute of Biomedical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Hares, Jonathan D [Kentech Instruments Ltd, Unit 9, Hall Farm Workshops, South Moreton, Didcot, Oxfordshire, OX11 9AG (United Kingdom)], E-mail: gordon.kennedy@imperial.ac.uk

    2008-05-07

    We demonstrate flexible use of low cost, high-power light emitting diodes as illumination sources for fluorescence lifetime imaging (FLIM). Both time-domain and frequency-domain techniques have been implemented at wavelengths spanning the range 450-640 nm. Additionally, we demonstrate optically sectioned fluorescence lifetime imaging by combining structured illumination with frequency-domain FLIM.

  4. High-Performance Single Nanowire Tunnel Diodes

    DEFF Research Database (Denmark)

    Wallentin, Jesper; Persson, Johan Mikael; Wagner, Jakob Birkedal

    2010-01-01

    We demonstrate single nanowire tunnel diodes with room temperature peak current densities of up to 329 A/cm(2). Despite the large surface to volume ratio of the type-II InP-GaAs axial heterostructure nanowires, we measure peak to valley current ratios (PVCR) of up to 8.2 at room temperature and 27...

  5. Microring Diode Laser for THz Generation

    DEFF Research Database (Denmark)

    Mariani, S.; Andronico, A.; Favero, I.

    2013-01-01

    We report on the modeling and optical characterization of AlGaAs/InAs quantum-dot microring diode lasers designed for terahertz (THz) difference frequency generation (DFG) between two whispering gallery modes (WGMs) around 1.3 $\\mu$m. In order to investigate the spectral features of this active...

  6. The Pierce-diode approximation to the single-emitter plasma diode

    International Nuclear Information System (INIS)

    Ender, A. Ya.; Kuhn, S.; Kuznetsov, V. I.

    2006-01-01

    The possibility of modeling fast processes in the collisionless single-emitter plasma diode (Knudsen diode with surface ionization, KDSI) by means of the Pierce-diode is studied. The KDSI is of practical importance in that it is an almost exact model of thermionic energy converters (TICs) in the collisionless regime and can also be used to model low-density Q-machines. At high temperatures, the Knudsen TIC comes close to the efficiency of the Carnot cycle and hence is the most promising converter of thermal to electric energy. TICs can be applied as component parts in high-temperature electronics. It is shown that normalizations must be chosen appropriately in order to compare the plasma characteristics of the two models: the KDSI and the Pierce-diode. A linear eigenmode theory of the KDSI is developed. For both nonlinear time-independent states and linear eigenmodes without electron reflection, excellent agreement is found between the analytical potential distributions for the Pierce-diode and the corresponding numerical ones for the KDSI. For the states with electron reflection, the agreement is satisfactory in a qualitative sense. A full classification of states of both diodes for the regimes with and without electron reflection is presented. The effect of the thermal spread in electron velocities on the potential distributions and the (ε,η) diagrams is analyzed. Generally speaking, the methodology developed is usefully applicable to a variety of systems in which the electrons have beam-like distributions

  7. The Beam Characteristics of High Power Diode Laser Stack

    Science.gov (United States)

    Gu, Yuanyuan; Fu, Yueming; Lu, Hui; Cui, Yan

    2018-03-01

    Direct diode lasers have some of the most attractive features of any laser. They are very efficient, compact, wavelength versatile, low cost, and highly reliable. However, the full utilization of direct diode lasers has yet to be realized. However, the poor quality of diode laser beam itself, directly affect its application ranges, in order to better use of diode laser stack, need a proper correction of optical system, which requires accurate understanding of the diode laser beam characteristics. Diode laser could make it possible to establish the practical application because of rectangular beam patterns which are suitable to make fine bead with less power. Therefore diode laser cladding will open a new field of repairing for the damaged machinery parts which must contribute to recycling of the used machines and saving of cost.

  8. Recent advancements in spectroscopy using tunable diode lasers

    International Nuclear Information System (INIS)

    Nasim, Hira; Jamil, Yasir

    2013-01-01

    Spectroscopy using tunable diode lasers is an area of research that has gone through a dramatic evolution over the last few years, principally because of new exciting approaches in the field of atomic and molecular spectroscopy. This article attempts to review major recent advancements in the field of diode laser based spectroscopy. The discussion covers the developments made so far in the field of diode lasers and illustrates comprehensively the properties of free-running diode lasers. Since the commercially available free-running diode lasers are not suitable for high-precision spectroscopic studies, various techniques developed so far for converting these free-running diode lasers into true narrow linewidth tunable laser sources are discussed comprehensively herein. The potential uses of diode lasers in different spectroscopic fields and their extensive list of applications have also been included, which may be interesting for the novice and the advanced user as well. (topical review)

  9. Photon response of silicon diode neutron detectors

    International Nuclear Information System (INIS)

    McCall, R.C.; Jenkins, T.M.; Oliver, G.D. Jr.

    1976-07-01

    The photon response of silicon diode neutron detectors was studied to solve the problem on detecting neutrons in the presence of high energy photons at accelerator neutron sources. For the experiment Si diodes, Si discs, and moderated activation foil detectors were used. The moderated activation foil detector consisted of a commercial moderator and indium foils 2'' in diameter and approximately 2.7 grams each. The moderator is a cylinder of low-density polyethylene 6 1 / 4 '' in diameter by 6 1 / 16 '' long covered with 0.020'' of cadmium. Neutrons are detected by the reaction 115 In (n,γ) 116 In(T/sub 1 / 2 / = 54 min). Photons cannot be detected directly but photoneutrons produced in the moderator assembly can cause a photon response. The Si discs were thin slices of single-crystal Si about 1.4 mils thick and 1'' in diameter which were used as activation detectors, subsequently being counted on a thin-window pancake G.M. counter. The Si diode fast neutron dosimeter 5422, manufactured by AB Atomenergi in Studsvik, Sweden, consists of a superdoped silicon wafer with a base width of 0.050 inches between two silver contacts coated with 2 mm of epoxy. For this experiment, the technique of measuring the percent change of voltage versus dose was used. Good precision was obtained using both unirradiated and preirradiated diodes. All diodes, calibrated against 252 CF in air,were read out 48 hours after irradiation to account for any room temperature annealing. Results are presented and discussed

  10. 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.

  11. Large area electron beam diode development

    International Nuclear Information System (INIS)

    Helava, H.; Gilman, C.M.; Stringfield, R.M.; Young, T.

    1983-01-01

    A large area annular electron beam diode has been tested at Physics International Co. on the multi-terawatt PITHON generator. A twelve element post hole convolute converted the coaxial MITL into a triaxial arrangement of anode current return structures both inside and outside the cathode structure. The presence of both inner and outer current return paths provide magnetic pressure balance for the beam, as determined by diode current measurements. X-ray pinhole photographs indicated uniform emission with intensity maxima between the post positions. Current losses in the post hole region were negligible, as evidenced by the absence of damage to the aluminum hardware. Radial electron flow near the cathode ring however did damage the inner anode cylinder between the post positions. Cutting away these regions prevented further damage of the transmission lines

  12. Efficient thermal diode with ballistic spacer

    Science.gov (United States)

    Chen, Shunda; Donadio, Davide; Benenti, Giuliano; Casati, Giulio

    2018-03-01

    Thermal rectification is of importance not only for fundamental physics, but also for potential applications in thermal manipulations and thermal management. However, thermal rectification effect usually decays rapidly with system size. Here, we show that a mass-graded system, with two diffusive leads separated by a ballistic spacer, can exhibit large thermal rectification effect, with the rectification factor independent of system size. The underlying mechanism is explained in terms of the effective size-independent thermal gradient and the match or mismatch of the phonon bands. We also show the robustness of the thermal diode upon variation of the model's parameters. Our finding suggests a promising way for designing realistic efficient thermal diodes.

  13. Pulsed diode source of polarized ions

    International Nuclear Information System (INIS)

    Katzenstein, J.; Rostoker, N.

    1983-01-01

    The advantages of polarized nuclei for fusion reactors have recently been described. We propose a pulsed source of polarized nuclei that consists of an ion diode with a polarized anode. With magnetic resonance techniques the nuclear spins of the protons of solid NH 3 can be made about 90 to 95% polarized. This material would be used for the anode. The diode would be pulsed with a voltage of 1-200K-volts for 1-2 μ sec. Flashover of the anode produces a surface plasma from which the polarized protons would be extracted to form a beam. Depolarization could be detected by comparing reaction cross sections and/or distribution of reaction products with similar results for unpolarized beams

  14. Diode line scanner for beam diagnostics

    International Nuclear Information System (INIS)

    Gustov, S.A.

    1987-01-01

    The device-scanning diode line is described. It is applied for beam profile measuring with space precision better than ± 0.5 mm and with discreteness of 3 mm along Y-axis and 0.25 mm along X-axis. The device is easy in construction, reliable and has a small time of information acquisition (2-5 min). The working range is from 100 to 10 6 rad/min (10 6 -10 10 part/mm 2 /s for 660 MeV protons). Radioresistance is 10 7 rad. The device can be applied for precise beam line element tuning at beam transporting and emittance measuring. The fixed diode line (a simplified device version) has smaller dimensions and smaller time of data acquisition (2-5 s). It is applied for quick preliminary beamline tuning. The flowsheet and different variants of data representation on beam profile are given

  15. Experimental diode laser-assisted microvascular anastomosis.

    Science.gov (United States)

    Reali, U M; Gelli, R; Giannotti, V; Gori, F; Pratesi, R; Pini, R

    1993-05-01

    An experimental study to evaluate a diode-laser approach to microvascular end-to-end anastomoses is reported. Studies were carried out on the femoral arteries and veins of Wistar rats, and effective welding of vessel tissue was obtained at low laser power, by enhancing laser absorption with indocyanine green (Cardio-green) solution. The histologic and surgical effects of this laser technique were examined and compared with those of conventional microvascular sutured anastomoses.

  16. Safety of light emitting diodes in toys.

    Science.gov (United States)

    Higlett, M P; O'Hagan, J B; Khazova, M

    2012-03-01

    Light emitting diodes (LEDs) are increasingly being used in toys. An assessment methodology is described for determining the accessible emission limits for the optical radiation from the toys, which takes account of expected use and reasonably foreseeable misuse of toys. Where data are available, it may be possible to assess the toy from the data sheet alone. If this information is not available, a simple measurement protocol is proposed.

  17. Safety of light emitting diodes in toys

    International Nuclear Information System (INIS)

    Higlett, M P; O'Hagan, J B; Khazova, M

    2012-01-01

    Light emitting diodes (LEDs) are increasingly being used in toys. An assessment methodology is described for determining the accessible emission limits for the optical radiation from the toys, which takes account of expected use and reasonably foreseeable misuse of toys. Where data are available, it may be possible to assess the toy from the data sheet alone. If this information is not available, a simple measurement protocol is proposed.

  18. An All-Silicon Passive Optical Diode

    OpenAIRE

    Fan, Li; Wang, Jian; Varghese, Leo T.; Shen, Hao; Niu, Ben; Xuan, Yi; Weiner, Andrew M.; Qi, Minghao

    2011-01-01

    A passive optical diode effect would be useful for on-chip optical information processing but has been difficult to achieve. Using a method based on optical nonlinearity, we demonstrate a forward-backward transmission ratio of up to 28 decibels within telecommunication wavelengths. Our device, which uses two silicon rings 5 micrometers in radius, is passive yet maintains optical nonreciprocity for a broad range of input power levels, and it performs equally well even if the backward input pow...

  19. Diode having trenches in a semiconductor region

    Energy Technology Data Exchange (ETDEWEB)

    Palacios, Tomas Apostol; Lu, Bin; Matioli, Elison de Nazareth

    2016-03-22

    An electrode structure is described in which conductive regions are recessed into a semiconductor region. Trenches may be formed in a semiconductor region, such that conductive regions can be formed in the trenches. The electrode structure may be used in semiconductor devices such as field effect transistors or diodes. Nitride-based power semiconductor devices are described including such an electrode structure, which can reduce leakage current and otherwise improve performance.

  20. Bicritical behaviors observed in coupled diode resonators

    International Nuclear Information System (INIS)

    Kim, Youngtae

    2004-01-01

    We have investigated bicritical behaviors of unidirectionally coupled diode resonators having a period doubling route to chaos. Depending on the dynamical states of the drive subsystem, the response subsystem showed a dynamical behavior other than that of the uncoupled system. The experimental results agreed well with the results obtained from the simulation of unidirectionally coupled logistic maps and oscillators. A new type of scaling behavior and a power spectrum of the hyperchaotic attractor appearing near a bicritical point were also observed.

  1. Diode-laser-illuminated automotive lamp systems

    Science.gov (United States)

    Marinelli, Michael A.; Remillard, Jeffrey T.

    1998-05-01

    We have utilized the high brightness of state-of-the-art diode laser sources, and a variety of emerging optical technologies to develop a new class of thin, uniquely styled automotive brake and signal lamps. Using optics based on thin (5 mm) plastic sheets, these lamps provide appearance and functional advantages not attainable with traditional automotive lighting systems. The light is coupled into the sheets using a 1 mm diameter glass fiber, and manipulated using refraction and reflection from edges, surfaces, and shaped cut-outs. Light can be extracted with an efficiency of approximately 50% and formed into a luminance distribution that meets the Society of Automotive Engineers (SAE) photometric requirements. Prototype lamps using these optics have been constructed and are less than one inch in thickness. Thin lamps reduce sheet metal costs, complexity, material usage, weight, and allow for increased trunk volume. In addition, these optics enhance lamp design flexibility. When the lamps are not energized, they can appear body colored, and when lighted, the brightness distribution across the lamp can be uniform or structured. A diode laser based brake lamp consumes seven times less electrical power than one using an incandescent source and has instant on capability. Also, diode lasers have the potential to be 10-year/150,000 mile light sources.

  2. Diode Laser Excision of Oral Benign Lesions.

    Science.gov (United States)

    Mathur, Ena; Sareen, Mohit; Dhaka, Payal; Baghla, Pallavi

    2015-01-01

    Lasers have made tremendous progress in the field of dentistry and have turned out to be crucial in oral surgery as collateral approach for soft tissue surgery. This rapid progress can be attributed to the fact that lasers allow efficient execution of soft tissue procedures with excellent hemostasis and field visibility. When matched to scalpel, electrocautery or high frequency devices, lasers offer maximum postoperative patient comfort. Four patients agreed to undergo surgical removal of benign lesions of the oral cavity. 810 nm diode lasers were used in continuous wave mode for excisional biopsy. The specimens were sent for histopathological examination and patients were assessed on intraoperative and postoperative complications. Diode laser surgery was rapid, bloodless and well accepted by patients and led to complete resolution of the lesions. The excised specimen proved adequate for histopathological examination. Hemostasis was achieved immediately after the procedure with minimal postoperative problems, discomfort and scarring. We conclude that diode lasers are rapidly becoming the standard of care in contemporary dental practice and can be employed in procedures requiring excisional biopsy of oral soft tissue lesions with minimal problems in histopathological diagnosis.

  3. Performance measurements of hybrid PIN diode arrays

    International Nuclear Information System (INIS)

    Jernigan, J.G.; Arens, J.F.; Collins, T.; Herring, J.; Shapiro, S.L.; Wilburn, C.D.

    1990-05-01

    We report on the successful effort to develop hybrid PIN diode arrays and to demonstrate their potential as components of vertex detectors. Hybrid pixel arrays have been fabricated by the Hughes Aircraft Co. by bump bonding readout chips developed by Hughes to an array of PIN diodes manufactured by Micron Semiconductor Inc. These hybrid pixel arrays were constructed in two configurations. One array format having 10 x 64 pixels, each 120 μm square, and the other format having 256 x 256 pixels, each 30 μm square. In both cases, the thickness of the PIN diode layer is 300 μm. Measurements of detector performance show that excellent position resolution can be achieved by interpolation. By determining the centroid of the charge cloud which spreads charge into a number of neighboring pixels, a spatial resolution of a few microns has been attained. The noise has been measured to be about 300 electrons (rms) at room temperature, as expected from KTC and dark current considerations, yielding a signal-to-noise ratio of about 100 for minimum ionizing particles. 4 refs., 13 figs

  4. Fine tuning power diodes with irradiation

    International Nuclear Information System (INIS)

    Tarneja, K.S.; Bartko, J.; Johnson, J.E.

    1976-01-01

    Diodes of a particular type are fine tuned with irradiation to optimize the reverse recovery time while minimizing forward voltage drop and providing more uniform electrical characcteristics. The initial and desired minority carrier lifetimes in the anode region of the type are determined as a function of forward voltage drop and reverse recovery time, and the minority carrier radiation damage factor is determined for a desired type of diode and radiation source. The radiation dosage to achieve the desired carrier lifetime with the radiation source is thereafter determined from the function 1/tau = 1/tau 0 + K phi, where tau is the desired minority carrier lifetime, tau 0 is the initial minority carrier lifetime, K is the determined minority carrier radiation damage factor and phi is the radiation dosage. A major surface and preferably the major surface adjoining the anode region of the diodes is then irradiated with the radiation source to the determined radiation dosage. Preferably, the radiation dosage is between about 1 X 10 12 and 5 X 10 13 e/cm 2 , with electron radiation of intensity between 1 and 3 MeV

  5. Analytic model of Applied-B ion diode impedance behavior

    International Nuclear Information System (INIS)

    Miller, P.A.; Mendel, C.W. Jr.

    1987-01-01

    An empirical analysis of impedance data from Applied-B ion diodes used in seven inertial confinement fusion research experiments was published recently. The diodes all operated with impedance values well below the Child's-law value. The analysis uncovered an unusual unifying relationship among data from the different experiments. The analysis suggested that closure of the anode-cathode gap by electrode plasma was not a dominant factor in the experiments, but was not able to elaborate the underlying physics. Here we present a new analytic model of Applied-B ion diodes coupled to accelerators. A critical feature of the diode model is based on magnetic insulation theory. The model successfully describes impedance behavior of these diodes and supports stimulating new viewpoints of the physics of Applied-B ion diode operation

  6. XUV preionization effects in high power magnetically insulated diodes

    International Nuclear Information System (INIS)

    Maenchen, J.; Woodworth, J.R.; Foltz, B.W.

    1985-01-01

    Electrode surface desorption and photoionization by an intense XUV pulse has been shown to dramatically improve a vacuum diode impedance history. The 6-Terawatt Applied-B ion diode experiment on PBFA I is limited by a delay in both diode and ion current initiation. The insulation magnetic field impedes electron crossings which are believed to aid the ion source initiation. The diode is therefore initially a severe overmatch to the accelerator 40-nsec, 2.2-MV, 0.5-ohm pulse. The diode current increases during the pulse, leading to a rapidly falling impedance history. The application of an intense (30 to 50-kW/cm 2 ) XUV flux from an array of sixteen 60-kA spark sources is found to cause immediate diode current flow, resulting in both a greatly improved impedance history and the prompt initiation of an intense higher power ion beam

  7. Common rectifier diodes in temperature measurement applications below 50 K

    International Nuclear Information System (INIS)

    Jaervelae, J; Stenvall, A; Mikkonen, R

    2010-01-01

    In this paper we studied the use of common electronic semiconductor diodes in temperature measurements at cryogenic atmosphere. The motivation for this is the high price of calibrated cryogenic temperature sensors since there are some applications, like quench detection, in which a cheaper and a less accurate sensor would suffice. We measured the forward voltage as a function of temperature, V f (T), of several silicon rectifier diodes to determine the accuracy and interchangeability of the diodes. The experimental results confirmed that V f (T) of common rectifier diodes are similar to cryogenic sensor diodes, but the variability between two samples is much larger. The interchangeability of the diodes proved to be poor if absolute temperatures are to be measured. However for sensing changes in temperature they proved to be adequate and thus can be used to measure e.g. quench propagation or sense quench ignition at multiple locations with cheap price.

  8. Trap-induced photoconductivity in singlet fission pentacene diodes

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Xianfeng, E-mail: qiaoxianfeng@hotmail.com; Zhao, Chen; Chen, Bingbing; Luan, Lin [WuHan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wu Han 430074 (China)

    2014-07-21

    This paper reports a trap-induced photoconductivity in ITO/pentacene/Al diodes by using current-voltage and magneto-conductance measurements. The comparison of photoconductivity between pentacene diodes with and without trap clearly shows that the traps play a critical role in generating photoconductivity. It shows that no observable photoconductivity is detected for trap-free pentacene diodes, while significant photoconductivity is observed in diodes with trap. This is because the initial photogenerated singlet excitons in pentacene can rapidly split into triplet excitons with higher binding energy prior to dissociating into free charge carriers. The generated triplet excitons react with trapped charges to release charge-carriers from traps, leading to a trap-induced photoconductivity in the single-layer pentacene diodes. Our studies elucidated the formation mechanisms of photoconductivity in pentacene diodes with extremely fast singlet fission rate.

  9. Light Converting Inorganic Phosphors for White Light-Emitting Diodes

    OpenAIRE

    Chen, Lei; Lin, Chun-Che; Yeh, Chiao-Wen; Liu, Ru-Shi

    2010-01-01

    White light-emitting diodes (WLEDs) have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or near-ultraviolet (nUV) LEDs) and photoluminescence phosphors. These solid-state LED lamps, rather than organic light emitting diode (OLED) or polymer light-emitting diode (PLED), have a number of advantages over conventional incand...

  10. Laser diagnostics on magnetically insulated flashover pulsed ion diodes

    International Nuclear Information System (INIS)

    Horioka, K.; Tazima, N.; Fukui, T.; Kasuya, K.

    1989-01-01

    Our recent experimental results on the characteristics of a flashover-type applied-B magnetically insulated pulsed ion diode are described. The main issues are to investigate the cause of impurity of the extracted beam and to examine the effect of neutral particles on the diode characteristics. In the experiment, our main efforts were placed on laser diagnostics of the diode gap behavior. (author)

  11. Plasma-filled diode based on the coaxial gun

    Science.gov (United States)

    Zherlitsyn, A. A.; Kovalchuk, B. M.; Pedin, N. N.

    2012-10-01

    The paper presents the results of studies of a coaxial gun for a plasma-filled electron diode. Effects of the discharge channel diameter and gun current on characteristics of the plasma and pulse generated in the diode were investigated. The electron beam with maximum energy of ≥1 MeV at the current of ≈100 kA was obtained in the experiments with a plasma-filled diode. The energy of ≈5 kJ with the peak power of ≥100 GW dissipated in the diode.

  12. Plasma filled diodes and application to a PEOS

    International Nuclear Information System (INIS)

    Grossmann, J.M.; Ottinger, P.F.; Drobot, A.T.; Seftor, L.

    1985-01-01

    Pinched beam diodes generally begin operation at large impedances until the diode has had time to turn on (at which point strong electric fields turn on electric emission at the cathode). Current turn-on is accompanied by a sharp drop in impedance and is accomplished initially through space charge limited flow. As the current increases, the diode impedance will be determined by critical current flow when the electron beam pinches. Eventually the diode shorts out by gap closure as the high density electrode plasmas expand cross the AK gap. After turn-on, then, the diode acts as a low impedance load which is favorable for coupling to a PEOS by allowing for strong insulation of the electron flow from the PEOS to the load. It would be advantageous when using a PEOS to have the impedance of the diode low even at early times. This can be accomplished by introducing a low density plasma in the region between the cathode and the anode. The plasma initially presents the PEOS with a low impedance current path at the load as the switch opens - thereby reducing current losses upstream of the load. As the switch opens, the impedance of the diode can increase as the diode plasma erodes away, and the diode gap opens

  13. Plasma-filled diode based on the coaxial gun.

    Science.gov (United States)

    Zherlitsyn, A A; Kovalchuk, B M; Pedin, N N

    2012-10-01

    The paper presents the results of studies of a coaxial gun for a plasma-filled electron diode. Effects of the discharge channel diameter and gun current on characteristics of the plasma and pulse generated in the diode were investigated. The electron beam with maximum energy of ≥1 MeV at the current of ≈100 kA was obtained in the experiments with a plasma-filled diode. The energy of ≈5 kJ with the peak power of ≥100 GW dissipated in the diode.

  14. Quasi-CW Laser Diode Bar Life Tests

    Science.gov (United States)

    Stephen, Mark A.; Krainak, Michael A.; Dallas, Joseph L.

    1997-01-01

    NASA's Goddard Space Flight Center is developing technology for satellite-based, high peak power, LIDAR transmitters requiring 3-5 years of reliable operation. Semi-conductor laser diodes provide high efficiency pumping of solid state lasers with the promise of long-lived, reliable operation. 100-watt quasi- CW laser diode bars have been baselined for the next generation laser altimeters. Multi-billion shot lifetimes are required. The authors have monitored the performance of several diodes for billions of shots and investigated operational modes for improving diode lifetime.

  15. Quaternary InGaAsSb Thermophotovoltaic Diodes

    International Nuclear Information System (INIS)

    MW Dashiell; JF Beausang; H Ehsani; GJ Nichols; DM Depoy; LR Danielson; P Talamo; KD Rahner; EJ Brown; SR Burger; PM Foruspring; WF Topper; PF Baldasaro; CA Wang; R Huang; M Connors; G Turner; Z Shellenbarger; G Taylor; J Li; R Martinelli; D Donetski; S Anikeev; G Belenky; S Luryi

    2006-01-01

    In x Ga 1-x As y Sb 1-y thermophotovoltaic (TPV) diodes were grown lattice-matched to GaSb substrates by Metal Organic Vapor Phase Epitaxy (MOVPE) in the bandgap range of E G = 0.5 to 0.6eV. InGaAsSb TPV diodes, utilizing front-surface spectral control filters, are measured with thermal-to-electric conversion efficiency and power density of η TPV = 19.7% and PD =0.58 W/cm 2 respectively for a radiator temperature of T radiator = 950 C, diode temperature of T diode = 27 C, and diode bandgap of E G = 0.53eV. Practical limits to TPV energy conversion efficiency are established using measured recombination coefficients and optical properties of front surface spectral control filters, which for 0.53eV InGaAsSb TPV energy conversion is η TPV = 28% and PD = 0.85W/cm 2 at the above operating temperatures. The most severe performance limits are imposed by (1) diode open-circuit voltage (VOC) limits due to intrinsic Auger recombination and (2) parasitic photon absorption in the inactive regions of the module. Experimentally, the diode V OC is 15% below the practical limit imposed by intrinsic Auger recombination processes. Analysis of InGaAsSb diode electrical performance vs. diode architecture indicate that the V OC and thus efficiency is limited by extrinsic recombination processes such as through bulk defects

  16. Plasma-filled diode based on the coaxial gun

    Energy Technology Data Exchange (ETDEWEB)

    Zherlitsyn, A. A.; Kovalchuk, B. M.; Pedin, N. N. [Institute of High Current Electronics, 2/3 Academichesky Avenue, 634055 Tomsk (Russian Federation)

    2012-10-15

    The paper presents the results of studies of a coaxial gun for a plasma-filled electron diode. Effects of the discharge channel diameter and gun current on characteristics of the plasma and pulse generated in the diode were investigated. The electron beam with maximum energy of {>=}1 MeV at the current of Almost-Equal-To 100 kA was obtained in the experiments with a plasma-filled diode. The energy of Almost-Equal-To 5 kJ with the peak power of {>=}100 GW dissipated in the diode.

  17. Plasma-filled diode based on the coaxial gun

    International Nuclear Information System (INIS)

    Zherlitsyn, A. A.; Kovalchuk, B. M.; Pedin, N. N.

    2012-01-01

    The paper presents the results of studies of a coaxial gun for a plasma-filled electron diode. Effects of the discharge channel diameter and gun current on characteristics of the plasma and pulse generated in the diode were investigated. The electron beam with maximum energy of ≥1 MeV at the current of ≈100 kA was obtained in the experiments with a plasma-filled diode. The energy of ≈5 kJ with the peak power of ≥100 GW dissipated in the diode.

  18. Investigation of Power Flow from a Plasma Opening Switch to an Electron Beam Diode

    National Research Council Canada - National Science Library

    Black, D

    1999-01-01

    ...) and an electron-beam (e-beam) diode load. The parameters that were varied independently in this set of experiments were the conduction time, the e-beam diode anode-cathode (A-K) gap (diode impedance...

  19. Diode laser prostatectomy (VLAP): initial canine evaluation

    Science.gov (United States)

    Kopchok, George E.; Verbin, Chris; Ayres, Bruce; Peng, Shi-Kaung; White, Rodney A.

    1995-05-01

    This study evaluated the acute and chronic effects of diode laser (960 nm) prostatectomy using a Prolase II fiber in a canine model (n equals 5). The laser fiber consists of a 1000 um quartz fiber which reflects a cone of laser energy, at 45 degree(s) to the axis of the fiber, into the prostatic urethra (Visual Laser Ablation of Prostate). Perineal access was used to guide a 15.5 Fr cystoscope to the level of the prostate. Under visual guidance and continual saline irrigation, 60 watts of laser power was delivered for 60 seconds at 3, 9, and 12 o'clock and 30 seconds at the 6 o'clock (posterior) positions for a total energy fluence of 12,600 J. One prostate received an additional 60 second exposure at 3 and 9 o'clock for a total fluence of 19,800 J. The prostates were evaluated at one day (n equals 1) and 8 weeks (n equals 4). The histopathology of laser effects at one day show areas of necrosis with loss of glandular structures and stromal edema. Surrounding this area was a zone of degenerative glandular structures extending up to 17.5 mm (cross sectional diameter). The histopathology of the 8 week laser treated animals demonstrated dilated prostatic urethras with maximum cross- sectional diameter of 23.4 mm (mean equals 18.5 +/- 3.9 mm). This study demonstrates the effectiveness of diode laser energy for prostatic tissue coagulation and eventual sloughing. The results also demonstrate the safety of diode laser energy, with similar tissue response as seen with Nd:YAG laser, for laser prostatectomy.

  20. Tunable Diode Laser Heterodyne Spectrophotometry of Ozone

    Science.gov (United States)

    Fogal, P. F.; McElroy, C. T.; Goldman, A.; Murcray, D. G.

    1988-01-01

    Tunable diode laser heterodyne spectrophotometry (TDLHS) has been used to make extremely high resolution (less than 0.0005/ cm) solar spectra in the 9.6 micron ozone band. Observations have shown that a signal-to-noise ratio of 95 : 1 (35% of theoretical) for an integration time of 1/8 second can be achieved at a resolution of 0.0005 wavenumbers. The spectral data have been inverted to yield a total column amount of ozone, in good agreement with that. measured at the nearby National Oceanographic and Atmospheric Administration (NOAA) ozone monitoring facility in Boulder, Colorado.

  1. Development on mini X-ray diode

    International Nuclear Information System (INIS)

    Jiang Shaoen; Sun Kexu; Peng Nengling; Huang Tianxuan; Cui Yanli; Yi Rongqing; Chen Jiusen

    2004-01-01

    The mini X-ray diode (M-XRD) was developed, and was used in mini soft X-ray spectrometer. Compared with traditional XRD, M-XRD's volume reduces to 1/30. M-XRD's property was experimentally examined on Shenguang II laser facility. The experimental results indicated that the temporal response and sensitivity of M-XRD are basically consistent with traditional XRD. The equivalent circuit of XRD was analyzed, and its response time and linear saturated current were calculated. (authors)

  2. Multifractal properties of resistor diode percolation.

    Science.gov (United States)

    Stenull, Olaf; Janssen, Hans-Karl

    2002-03-01

    Focusing on multifractal properties we investigate electric transport on random resistor diode networks at the phase transition between the nonpercolating and the directed percolating phase. Building on first principles such as symmetries and relevance we derive a field theoretic Hamiltonian. Based on this Hamiltonian we determine the multifractal moments of the current distribution that are governed by a family of critical exponents [psi(l)]. We calculate the family [psi(l)] to two-loop order in a diagrammatic perturbation calculation augmented by renormalization group methods.

  3. Evaluation of automatic densitometer with laser diode

    International Nuclear Information System (INIS)

    Larrea Cox, Pedro J.; Hernandez Tabares, Lorenzo; Suarez San Pedro, Cirilo E.; Vazquez Cano, Aradys; Reyes Rodriguez, Marlen de los

    2009-01-01

    The evaluation of a prototype of an automatic transmission scanning densitometer is presented. It contains a semiconductor diode laser as a light source, and is mainly oriented to the analysis of protein electrophoresis. It was developed on the Center for Technological Applications and Nuclear Development (CEADEN). Its technical specifications were established and certified by the National Institute of Researches on Metrology (INIMET), and also the equipment was submitted for assays to the Process Control Laboratory, that belongs to the 'Adalberto Pesant' Enterprise for Sera and Hemo derivatives Products, in Havana city, where it was employed to the partial quality control of products that are made there, achieving satisfactory results. (Author)

  4. Efficient organic light emitting-diodes (OLEDs)

    CERN Document Server

    Chang, Yi-Lu

    2015-01-01

    Following two decades of intense research globally, the organic light-emitting diode (OLED) has steadily emerged as the ultimate display technology of choice for the coming decades. Portable active matrix OLED displays have already become prevalent, and even large-sized ultra-high definition 4K TVs are being mass-produced. More exotic applications such as wearable displays have been commercialized recently. With the burgeoning success in displays, researchers are actively bringing the technology forward into the exciting solid-state lighting market. This book presents the knowledge needed for

  5. Laser materials processing with diode lasers

    OpenAIRE

    Li, Lin; Lawrence, Jonathan; Spencer, Julian T.

    1996-01-01

    Laser materials processing is currently dominated by CO2, Nd-YAG and Excimer lasers. Continuous advances in semiconductor laser technology over the last decade have increased the average power output of the devices annualy by two fold, resulting in the commercial availability of the diode lasers today with delivery output powers in excess of 60W in CW mode and 5kW in qasi-CW mode. The advantages of compactness, high reliability, high efficiency and potential low cost, due to the mass producti...

  6. Junction depth dependence of breakdown in silicon detector diodes

    International Nuclear Information System (INIS)

    Beck, G.A.; Carter, A.A.; Carter, J.R.; Greenwood, N.M.; Lucas, A.D.; Munday, D.J.; Pritchard, T.W.; Robinson, D.; Wilburn, C.D.; Wyllie, K.

    1996-01-01

    The high voltage capability of detector diodes fabricated in the planar process is limited by the high field generated at the edge of the junction.We have fabricated diodes with increased junction depth with respect to our standard process and find a significantly higher breakdown voltage,in reasonable agreement with previous studies of junction breakdown. (orig.)

  7. Zener diode controls switching of large direct currents

    Science.gov (United States)

    1965-01-01

    High-current zener diode is connected in series with the positive input terminal of a dc supply to block the flow of direct current until a high-frequency control signal is applied across the zener diode. This circuit controls the switching of large dc signals.

  8. A novel diode laser system for photodynamic therapy

    DEFF Research Database (Denmark)

    Samsøe, E.; Andersen, P. E.; Petersen, P.

    2001-01-01

    In this paper a novel diode laser system for photodynamic therapy is demonstrated. The system is based on linear spatial filtering and optical phase conjugate feedback from a photorefractive BaTiO3 crystal. The spatial coherence properties of the diode laser are significantly improved. The system...

  9. Electron sheath collapse in an applied-B ion diode

    International Nuclear Information System (INIS)

    Grechikha, A.V.

    1996-01-01

    The effect of the electron sheath collapse in an applied-B ion diode due to the presence of the resistive anode plasma layer was found. This effect is more damaging at higher diode voltages and may be responsible for the parasitic load effect observed in the experiments. (author). 4 figs., 2 refs

  10. Nonimaging concentrators for diode-pumped slab lasers

    Science.gov (United States)

    Lacovara, Philip; Gleckman, Philip L.; Holman, Robert L.; Winston, Roland

    1991-10-01

    Diode-pumped slab lasers require concentrators for high-average power operation. We detail the properties of diode lasers and slab lasers which set the concentration requirements and the concentrator design methodologies that are used, and describe some concentrator designs used in high-average power slab lasers at Lincoln Laboratory.

  11. Operation of AC Adapters Visualized Using Light-Emitting Diodes

    Science.gov (United States)

    Regester, Jeffrey

    2016-01-01

    A bridge rectifier is a diamond-shaped configuration of diodes that serves to convert alternating current(AC) into direct current (DC). In our world of AC outlets and DC electronics, they are ubiquitous. Of course, most bridge rectifiers are built with regular diodes, not the light-emitting variety, because LEDs have a number of disadvantages. For…

  12. The electron irradiation effects in different structures of diodes

    International Nuclear Information System (INIS)

    Li Quanfen; Wang Jiaxu

    1993-01-01

    This paper describes the different electron irradiation effects in different structures of diodes and the different results produced by different irradiation ways. From this work, we can know how to choose proper manufacture arts and comprehensive factors according to the structures of diodes and the irradiation conditions

  13. Compact green-diode-based lasers for biophotonic bioimaging

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Hansen, Anders Kragh; Petersen, Paul Michael

    2014-01-01

    Diode lasers simultaneously offer tunability, high-power emission, and compact size at fairly low cost and are increasingly preferred for pumping titanium:sapphire lasers.......Diode lasers simultaneously offer tunability, high-power emission, and compact size at fairly low cost and are increasingly preferred for pumping titanium:sapphire lasers....

  14. Diode Laser for Laryngeal Surgery: a Systematic Review.

    Science.gov (United States)

    Arroyo, Helena Hotz; Neri, Larissa; Fussuma, Carina Yuri; Imamura, Rui

    2016-04-01

    Introduction The diode laser has been frequently used in the management of laryngeal disorders. The portability and functional diversity of this tool make it a reasonable alternative to conventional lasers. However, whether diode laser has been applied in transoral laser microsurgery, the ideal parameters, outcomes, and adverse effects remain unclear. Objective The main objective of this systematic review is to provide a reliable evaluation of the use of diode laser in laryngeal diseases, trying to clarify its ideal parameters in the larynx, as well as its outcomes and complications. Data Synthesis We included eleven studies in the final analysis. From the included articles, we collected data on patient and lesion characteristics, treatment (diode laser's parameters used in surgery), and outcomes related to the laser surgery performed. Only two studies were prospective and there were no randomized controlled trials. Most of the evidence suggests that the diode laser can be a useful tool for treatment of different pathologies in the larynx. In this sense, the parameters must be set depending on the goal (vaporization, section, or coagulation) and the clinical problem. The literature lacks studies on the ideal parameters of the diode laser in laryngeal surgery. The available data indicate that diode laser is a useful tool that should be considered in laryngeal surgeries. Thus, large, well-designed studies correlated with diode compared with other lasers are needed to better estimate its effects.

  15. Electron sheath collapse in an applied-B ion diode

    Energy Technology Data Exchange (ETDEWEB)

    Grechikha, A V [Forschungszentrum Karlsruhe (Germany). Institut fuer Neutronenphysik und Reaktortechnik

    1997-12-31

    The effect of the electron sheath collapse in an applied-B ion diode due to the presence of the resistive anode plasma layer was found. This effect is more damaging at higher diode voltages and may be responsible for the parasitic load effect observed in the experiments. (author). 4 figs., 2 refs.

  16. Asymmetric anode and cathode extraction structure fast recovery diode

    Science.gov (United States)

    Xie, Jiaqiang; Ma, Li; Gao, Yong

    2018-05-01

    This paper presents an asymmetric anode structure and cathode extraction fast and soft recovery diode. The device anode is partial-heavily doped and partial-lightly doped. The P+ region is introduced into the cathode. Firstly, the characteristics of the diode are simulated and analyzed. Secondly, the diode was fabricated and its characteristics were tested. The experimental results are in good agreement with the simulation results. The results show that, compared with the P–i–N diode, although the forward conduction characteristic of the diode is declined, the reverse recovery peak current is reduced by 47%, the reverse recovery time is shortened by 20% and the softness factor is doubled. In addition, the breakdown voltage is increased by 10%. Project supported by the National Natural Science Foundation of China (No. 51177133).

  17. Production of ion beam by conical pinched electron beam diode

    International Nuclear Information System (INIS)

    Matsukawa, Y.; Nakagawa, Y.

    1982-01-01

    Some properties of the ion beam produced by pinched electron beam diode having conical shape electrodes and organic insulator anode was studied. Ion energy is about 200keV and the peak diode current is about 30 kA. At 11cm from the diode apex, not the geometrical focus point, concentrated ion beam was obtained. Its density is more than 500A/cm 2 . The mean ion current density within the radius of 1.6cm around the axis from conical diode is two or three times that from an usual pinched electron beam diode with flat parallel electrodes of same dimension and impedance under the same conditions. (author)

  18. Silicon monolithic microchannel-cooled laser diode array

    International Nuclear Information System (INIS)

    Skidmore, J. A.; Freitas, B. L.; Crawford, J.; Satariano, J.; Utterback, E.; DiMercurio, L.; Cutter, K.; Sutton, S.

    2000-01-01

    A monolithic microchannel-cooled laser diode array is demonstrated that allows multiple diode-bar mounting with negligible thermal cross talk. The heat sink comprises two main components: a wet-etched Si layer that is anodically bonded to a machined glass block. The continuous wave (cw) thermal resistance of the 10 bar diode array is 0.032 degree sign C/W, which matches the performance of discrete microchannel-cooled arrays. Up to 1.5 kW/cm 2 is achieved cw at an emission wavelength of ∼808 nm. Collimation of a diode array using a monolithic lens frame produced a 7.5 mrad divergence angle by a single active alignment. This diode array offers high average power/brightness in a simple, rugged, scalable architecture that is suitable for large two-dimensional areas. (c) 2000 American Institute of Physics

  19. Diode-Assisted Buck-Boost Voltage-Source Inverters

    DEFF Research Database (Denmark)

    Gao, Feng; Loh, Poh Chiang; Teodorescu, Remus

    2009-01-01

    , a number of diode-assisted inverter variants can be designed with each having its own operational principle and voltage gain expression. For controlling them, a generic modulation scheme that can be used for controlling all diode-assisted variants with minimized harmonic distortion and component stress......This paper proposes a number of diode-assisted buck-boost voltage-source inverters with a unique X-shaped diode-capacitor network inserted between the inverter circuitry and dc source for producing a voltage gain that is comparatively higher than those of other buck-boost conversion techniques....... Using the diode-assisted network, the proposed inverters can naturally configure themselves to perform capacitive charging in parallel and discharging in series to give a higher voltage multiplication factor without compromising waveform quality. In addition, by adopting different front-end circuitries...

  20. Diode Laser Application in Soft Tissue Oral Surgery

    Science.gov (United States)

    Azma, Ehsan; Safavi, Nassimeh

    2013-01-01

    Introduction: Diode laser with wavelengths ranging from 810 to 980 nm in a continuous or pulsed mode was used as a possible instrument for soft tissue surgery in the oral cavity. Discussion: Diode laser is one of laser systems in which photons are produced by electric current with wavelengths of 810, 940 and 980nm. The application of diode laser in soft tissue oral surgery has been evaluated from a safety point of view, for facial pigmentation and vascular lesions and in oral surgery excision; for example frenectomy, epulis fissuratum and fibroma. The advantages of laser application are that it provides relatively bloodless surgical and post surgical courses with minimal swelling and scarring. We used diode laser for excisional biopsy of pyogenic granuloma and gingival pigmentation. Conclusion: The diode laser can be used as a modality for oral soft tissue surgery PMID:25606331

  1. High-power green diode laser systems for biomedical applications

    DEFF Research Database (Denmark)

    Müller, André

    propagation parameters and therefore efficiently increases the brightness of compact and cost-effective diode laser systems. The condition of overlapping beams is an ideal scenario for subsequent frequency conversion. Based on sum-frequency generation of two beam combined diode lasers a 3.2 fold increase...... output power of frequency doubled single emitters is limited by thermal effects potentially resulting in laser degradation and failure. In this work new concepts for power scaling of visible diode laser systems are introduced that help to overcome current limitations and enhance the application potential....... Implementing the developed concept of frequency converted, beam combined diode laser systems will help to overcome the high pump thresholds for ultrabroad bandwidth titanium sapphire lasers, leading towards diode based high-resolution optical coherence tomography with enhanced image quality. In their entirety...

  2. Development of a semiconductor neutron dosimeter with a PIN diode

    International Nuclear Information System (INIS)

    Kim, Seungho; Lee, Namho; Cho, Jaiwan; Youk, Geunuck

    2004-01-01

    When a Si PIN diode is exposed to fast neutrons, it produces displacement in Si lattice structure of the diode. Defects induced from structural dislocation become effective recombination centers for carriers which pass through the base of a PIN diode. Hence, increasing the resistivity of the diode decreases the current for the applied forward voltage. This paper involves the development of a neutron sensor based on the phenomena of the displacement effect damaged by neutron exposure. The neutron effect on the semiconductor was analyzed, and multi PIN diode arrays with various intrinsic layer (I layer) thicknesses and cross sections were fabricated. Under irradiation tests with a neutron beam, the manufactured diodes have good characteristics of linearity in a neutron irradiation experiment and give results that the increase of thickness of I layer and the decrease of the cross-section of the PIN diodes improve the sensitivity. Newly developed PIN diodes with a thicker I layer and various cross sections were retested and showed the best neutron sensitivity in the condition that the I layer thickness was similar to the length of a side of the cross-section. On the basis of two test results, final PIN diodes with a rectangular shape were manufactured and the characteristics for neutron detectors were analyzed through the neutron beam test using the on-line electronic dosimetry system. The developed PIN diode shows a good linearity to absorbed dose in the range of 0 to 1,000cGy (Tissue) and its neutron sensitivity is 13 mV/cGy at a constant current of 5 mA, that is three higher than that of similar commercially developed neutron detectors. Moreover the device shows less dependency on the orientation of the neutron beam and a considerable stability in an annealing test for a long period. (author)

  3. Patient dosimetry quality assurance program with a commerical diode system

    International Nuclear Information System (INIS)

    Lee, P.C.; Sawicka, J.M.; Glasgow, G.P.

    1994-01-01

    The purpose was to evaluate a commercial silicone diode dosimeter for a patient dosimetry quality assurance program. The diode dosimeter was calibrated against an ion chamber, and percentage depth dose, linearity, anisotrophy, virtual source position, and field size factor studies were performed. Correction factors for lack of full scatter medium in the diode entrance and exit dose measurements were acquired. Dosimetry equations were proposed for calculation of dose delivered at isocenter. Diode dose accuracy and reproducibility were tested on phantom and on four patients. A patient dosimetry quality assurance program based on diode-measured dose was instituted and patient dose data were collected. Diode measured percentage depth dose and field factors agreed to within 3% with those measured with an ion chamber. The diode exhibited less than 1.7% angular dose anisotrophy and less than 0.5% nonlinearity up to 4 Gy. Diode dose measurements in phantom showed that the calculated doses differed from the prescribed dose by less than 1.%; the diode exhibited a daily dose reproducibility of better than 0.2%. On four selected patients, the measured dose reproducibility was 1.5%; the average calculated doses were all within ± 7% of the prescribed doses. For 33 of 40 patients treated with a 6 MW beam, measured doses were within ± 7% of the prescribed doses. For 11 out of 12 patients, a second repeat measurements yielded doses within ± 7% of the prescribed doses. The proposed diode-based patient dosimetry quality assurance program with dose tolerance at ± 7% is simple and feasible. It is capable of detecting certain serious treatment errors such as incorrect daily dose greater than 7%, incorrect wedge use, incorrect photon energy and patient setup errors involving some incorrect source-to-surface-distance vs. source-to-axis-distance treatments. 13 refs., 5 figs., 5 tabs

  4. Electron beam diodes using ferroelectric cathodes

    International Nuclear Information System (INIS)

    Ivers, J.D.; Schaechter, L.; Nation, J.A.; Kerslick, G.S.

    1993-01-01

    A new high current density electron source is investigated. The source consists of a polarized ceramic disk with aluminum electrodes coated on both faces. The front electrode is etched in a periodic grid to expose the ceramic beneath. A rapid change in the polarization state of the ceramic results in the emission of a high density electron cloud into a 1 to 10mm diode gap. The anode potential is maintained by a charged transmission line. Some of the emitted electrons traverse the gap and an electron current flows. The emitted electron current has been measured as a function of the gap spacing and the anode potential. Current densities in excess of 70 A/cm 2 have been measured. The current is found to vary linearly with the anode voltage for gaps < 10 mm, and exceeds the Child-Langmuir current by at least two orders of magnitude. The experimental data will be compared with predictions from a model based on the emission of a cloud of electrons from the ferroelectric which in turn reflex in the diode gap

  5. Low level diode laser accelerates wound healing.

    Science.gov (United States)

    Dawood, Munqith S; Salman, Saif Dawood

    2013-05-01

    The effect of wound illumination time by pulsed diode laser on the wound healing process was studied in this paper. For this purpose, the original electronic drive circuit of a 650-nm wavelength CW diode laser was reconstructed to give pulsed output laser of 50 % duty cycle and 1 MHz pulse repetition frequency. Twenty male mice, 3 months old were used to follow up the laser photobiostimulation effect on the wound healing progress. They were subdivided into two groups and then the wounds were made on the bilateral back sides of each mouse. Two sessions of pulsed laser therapy were carried along 15 days. Each mice group wounds were illuminated by this pulsed laser for 12 or 18 min per session during these 12 days. The results of this study were compared with the results of our previous wound healing therapy study by using the same type of laser. The mice wounds in that study received only 5 min of illumination time therapy in the first and second days of healing process. In this study, we found that the wounds, which were illuminated for 12 min/session healed in about 3 days earlier than those which were illuminated for 18 min/session. Both of them were healed earlier in about 10-11 days than the control group did.

  6. Ion divergence in magnetically insulated diodes

    International Nuclear Information System (INIS)

    Slutz, S.A.; Lemke, R.W.; Pointon, T.D.; Desjarlais, M.P.; Johnson, D.J.; Mehlhorn, T.A.; Filuk, A.; Bailey, J.

    1995-01-01

    Magnetically insulated ion diodes are being developed to drive inertial confinement fusion. Ion beam microdivergence must be reduced to achieve the very high beam intensities required to achieve this goal. Three-dimensional particle-in-cell simulations indicate that instability induced fluctuations can produce significant ion divergence during acceleration. These simulations exhibit a fast growing mode early in time, which has been identified as the diocotron instability. The divergence generated by this mode is modest due to the relatively high frequency (>1GHz). Later, a low-frequency low-phase-velocity instability develops. This instability couples effectively to the ions, since the frequency is approximately the reciprocal of the ion transit time, and can generate unacceptably large ion divergences (>30 mrad). Linear stability theory reveals that this mode requires perturbations parallel to the applied magnetic field and is related to the modified two stream instability. Measurements of ion density fluctuations and energy-momentum correlations have confirmed that instabilities develop in ion diodes and contribute to the ion divergence. In addition, spectroscopic measurements indicate that the ions have a significant transverse temperature very close to the emission surface. Passive lithium fluoride (LiF) anodes have larger transverse beam temperatures than laser irradiated active sources. Calculations of source divergence expected from the roughness of LiF surfaces and the possible removal of this layer is presented

  7. Processes governing pinch formation in diodes

    International Nuclear Information System (INIS)

    Blaugrund, A.E.; Cooperstein, G.; Goldstein, S.A.

    1975-01-01

    The process of pinch formation in large aspect ratio diodes has been studied by means of streak photography and time-resolved x-ray detectors. A tight pinch is formed at the anode center by a collapsing thin hollow electron beam. The collapse velocity depends, among other things, on the type of material in the top 1 μm layer of the anode. In a tentative model it is assumed that an anode plasma is at least partially created from gases released from the surface layer of the anode by the heating action of the beam. These gases are ionized by primary, backscattered, and secondary electrons. Ions emitted from this plasma modify the electron trajectories in the diode leading to a radial collapse of the hollow electron beam. The observed monotonic dependence of the collapse velocity on the atomic number of the anode material can be explained by the smooth dependence on Z of both the specific heat and the electron backscatter coefficient. In the case of high-Z anodes the ion expansion time appears to be the factor limiting the collapse velocity. Detailed experimental data are presented

  8. Visible high power fiber coupled diode lasers

    Science.gov (United States)

    Köhler, Bernd; Drovs, Simon; Stoiber, Michael; Dürsch, Sascha; Kissel, Heiko; Könning, Tobias; Biesenbach, Jens; König, Harald; Lell, Alfred; Stojetz, Bernhard; Löffler, Andreas; Strauß, Uwe

    2018-02-01

    In this paper we report on further development of fiber coupled high-power diode lasers in the visible spectral range. New visible laser modules presented in this paper include the use of multi single emitter arrays @ 450 nm leading to a 120 W fiber coupled unit with a beam quality of 44 mm x mrad, as well as very compact modules with multi-W output power from 405 nm to 640 nm. However, as these lasers are based on single emitters, power scaling quickly leads to bulky laser units with a lot of optical components to be aligned. We also report on a new approach based on 450 nm diode laser bars, which dramatically reduces size and alignment effort. These activities were performed within the German government-funded project "BlauLas": a maximum output power of 80 W per bar has been demonstrated @ 450 nm. We show results of a 200 μm NA0.22 fiber coupled 35 W source @ 450 nm, which has been reduced in size by a factor of 25 compared to standard single emitter approach. In addition, we will present a 200 μm NA0.22 fiber coupled laser unit with an output power of 135 W.

  9. Angle sensitive single photon avalanche diode

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Changhyuk, E-mail: cl678@cornell.edu; Johnson, Ben, E-mail: bcj25@cornell.edu; Molnar, Alyosha, E-mail: am699@cornell.edu [Electrical and Computer Engineering, Cornell University, Ithaca, New York 14850 (United States)

    2015-06-08

    An ideal light sensor would provide exact information on intensity, timing, location, and angle of incoming photons. Single photon avalanche diodes (SPADs) provide such desired high (single photon) sensitivity with precise time information and can be implemented at a pixel-scale to form an array to extract spatial information. Furthermore, recent work has demonstrated photodiode-based structures (combined with micro-lenses or diffraction gratings) that are capable of encoding both spatial and angular information of incident light. In this letter, we describe the implementation of such a grating structure on SPADs to realize a pixel-scale angle-sensitive single photon avalanche diode (A-SPAD) built in a standard CMOS process. While the underlying SPAD structure provides high sensitivity, the time information of the two layers of diffraction gratings above offers angle-sensitivity. Such a unique combination of SPAD and diffraction gratings expands the sensing dimensions to pave a path towards lens-less 3-D imaging and light-field time-of-flight imaging.

  10. Production of intense negative ion beams in magnetically insulated diodes

    International Nuclear Information System (INIS)

    Lindenbaum, H.

    1988-01-01

    Production of intense negative ion beams in magnetically insulated diodes was studied in order to develop an understanding of this process by measuring the ion-beam parameters as a function of diode and cathode plasma conditions in different magnetically insulated diodes. A coral diode, a racetrack diode, and an annular diode were used. The UCI APEX pulse line, with a nominal output of 1MV, 140kA, was used under matched conditions with a pulse length of 50 nsec. Negative-ion intensity and divergence were measured with Faraday cups and CR-39 track detectors. Cathode plasma was produced by passive dielectric cathodes and later, by an independent plasma gun. Negative-ion currents had an intensity of a few A/cm 2 with a divergence ranging between a few tenths milliradians for an active TiH 2 plasma gun and 300 milliradians for a passive polyethelene cathode. Negative ions were usually emitted from a few hot spots on the cathode surface. These hot spots are believed to cause transverse electrical fields in the diode gap responsible for the beam divergence. Mass spectrometry measurements showed that the ion beam consists of mainly H - ions when using a polyethelene or a TiH 2 cathodes, and mainly of negative carbon ions when using a carbon cathode

  11. 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...

  12. Respiratory complications after diode-laser-assisted tonsillotomy.

    Science.gov (United States)

    Fischer, Miloš; Horn, Iris-Susanne; Quante, Mirja; Merkenschlager, Andreas; Schnoor, Jörg; Kaisers, Udo X; Dietz, Andreas; Kluba, Karsten

    2014-08-01

    Children with certain risk factors, such as comorbidities or severe obstructive sleep apnea syndrome (OSAS) are known to require extended postoperative monitoring after adenotonsillectomy. However, there are no recommendations available for diode-laser-assisted tonsillotomy. A retrospective chart review of 96 children who underwent diode-laser-assisted tonsillotomy (07/2011-06/2013) was performed. Data for general and sleep apnea history, power of the applied diode-laser (λ = 940 nm), anesthesia parameters, the presence of postoperative respiratory complications and postoperative healing were evaluated. After initially uncomplicated diode-laser-assisted tonsillotomy, an adjustment of post-anesthesia care was necessary in 16 of 96 patients due to respiratory failure. Respiratory complications were more frequent in younger children (3.1 vs. 4.0 years, p = 0.049, 95 % CI -1.7952 to -0.0048) and in children who suffered from nocturnal apneas (OR = 5.00, p diode-laser power higher than 13 W could be identified as a risk factor for the occurrence of a postoperative oropharyngeal edema (OR = 3.45, p diode-laser-assisted tonsillotomy. We recommend a reduced diode-laser power (<13 W) to reduce oropharyngeal edema.

  13. Investigation of Diode Pumped Alkali Laser Atmospheric Transmission Using Tunable Diode Laser Absorption Spectroscopy

    Science.gov (United States)

    2012-09-01

    Optics Letters, 28(23):2336–2338, 2003. 48. Lavan, M. “High Energy Laser Systems for Short Range Defense”. Acta Physica Polonica -Series A General Physics...able diode laser spectrometer for the remote sensing of vehicle emissions”. Spec- trochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 60...P. “A review of recent advances in semiconductor laser based gas mon- itors”. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 54

  14. 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.

  15. Performance of EPI diodes as dosimeters for photon beam radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Thais C. dos; Bizetto, Cesar A., E-mail: ccbueno@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Neves-Junior, Wellington F.P.; Haddad, Cecilia M.K. [Hospital Sirio Libanes (HSL), Sao Paulo, SP (Brazil); Goncalves, Josemary A.C.; Bueno, Carmen C. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Pontificia Universidade Catolica de Sao Paulo (PUC-SP), SP (Brazil)

    2011-07-01

    In this work we present the preliminary results about the performance of an epitaxial (EPI) diode as on-line dosimeter for photon beam radiotherapy. The diode used was processed at University of Hamburg on n-type 75 {mu}m thick epitaxial silicon layer grown on a highly doped n-type 300 {mu}m thick Czochralski (Cz) silicon substrate. The measurements were performed with a diode which not received any type of pre-dose. In order to use this device as a dosimeter, it was enclosed in a black polymethylmethacrylate (PMMA) probe. The diode was connected to an electrometer Keithley 6517B in the photovoltaic mode. During all measurements, the diode was held between PMMA plates, placed at 10.0 cm depth and centered in a radiation field of 10 x 10 cm{sup 2}, with the source-to-surface distance (SSD) kept at 100 cm. The short-term repeatability was measured with photon beams of 6 and 18 MV energy by registering five consecutive current signals for the same radiation dose. The current signals induced showed good instantaneous repeatability of the diode, characterized by a smallest coefficient of variation (CV) of 0.21%. Furthermore, the dose-response curves of the diode were quite linear with the highest charge sensitivity achieved of 5.0 {mu}C/Gy. It worth noting that still remains to be investigated the pre-dose influence on epitaxial silicon diode response in radiotherapy photon beam dosimetry, the long term stability and the radiation hardness of these diodes for absorbed doses higher than that investigated in this work. All these studies are under way. (author)

  16. Pulse power applications of silicon diodes in EML capacitive pulsers

    Science.gov (United States)

    Dethlefsen, Rolf; McNab, Ian; Dobbie, Clyde; Bernhardt, Tom; Puterbaugh, Robert; Levine, Frank; Coradeschi, Tom; Rinaldi, Vito

    1993-01-01

    Crowbar diodes are used for increasing the energy transfer from capacitive pulse forming networks. They also prevent voltage reversal on the energy storage capacitors. 52 mm diameter diodes with a 5 kV reverse blocking voltage, rated 40 kA were successfully used for the 32 MJ SSG rail gun. An uprated diode with increased current capability and a 15 kV reverse blocking voltage has been developed. Transient thermal analysis has predicted the current ratings for different pulse length. Analysis verification is obtained from destructive testing.

  17. Design, fabrication and testing of a thermal diode

    Science.gov (United States)

    Swerdling, B.; Kosson, R.

    1972-01-01

    Heat pipe diode types are discussed. The design, fabrication and test of a flight qualified diode for the Advanced Thermal Control Flight Experiment (ATFE) are described. The review covers the use of non-condensable gas, freezing, liquid trap, and liquid blockage techniques. Test data and parametric performance are presented for the liquid trap and liquid blockage techniques. The liquid blockage technique was selected for the ATFE diode on the basis of small reservoir size, low reverse mode heat transfer, and apparent rapid shut-off.

  18. Diode laser spectroscopy of oxygen electronic band at 760 nm

    International Nuclear Information System (INIS)

    Lucchesini, A.; De Rosa, M.; Gozzini, S.

    1998-01-01

    Collisional broadening and shift coefficients have been obtained by analyzing the line shapes of oxygen absorptions in the 760 nm electronic band. By using a diode laser spectrometer with commercially available etherostructure Al x Ga 1-x As diode lasers operating in 'free-running mode', line shape parameters have been collected at room temperature by varying the gas pressure. A systematic study has been carried on seven absorption lines by scanning the diode laser emission wavelength around the gas resonances. The weak absorption lines have been detected by using the wavelength modulation (WM) spectroscopy technique with second-harmonic detection

  19. Study of PIN diode energy traps created by neutrons

    International Nuclear Information System (INIS)

    Sopko, V; Dammer, J; Sopko, B; Chren, D

    2013-01-01

    Characterization of radiation defects is still ongoing and finds greater application in the increasing radiation doses on semiconductor detectors in experiments. Studying the changes of silicon PIN diode for high doses of radiation is the fundamental motivation for our measurements. In this article we describe the behavior of the PIN diode and development of the disorder caused by neutrons from a 252Cf and doses up to 8 Gy. The calibration curve for PIN diode shows the effect of disorders as the changes of the voltampere characteristics depending on the dose of neutron irradiation. The measured values for defects are in good agreement with created energy traps.

  20. A transient model of a cesium-barium diode

    International Nuclear Information System (INIS)

    Luke, J.R.; El-Genk, M.S.

    1995-01-01

    In this work a transient model of a Cs-Ba diode is developed, and a series of experiments is performed using a diode equipped with Langmuir probes. The Langmuir probe data show that the electron energy distribution is non-Maxwellian at low discharge currents, indicating the presence of an electron beam from the emitter. Experimental results also showed that the plasma properties are non-homogeneous across the 1 mm diode gap; the electron temperature and plasma potential were higher near the emitter and the plasma density was higher near the collector. Experimental evidence is presented to show that the discharge contracts to a filament below the maximum thermal emission current

  1. Photoluminescence excitation measurements using pressure-tuned laser diodes

    Science.gov (United States)

    Bercha, Artem; Ivonyak, Yurii; Medryk, Radosław; Trzeciakowski, Witold A.; Dybała, Filip; Piechal, Bernard

    2015-06-01

    Pressure-tuned laser diodes in external cavity were used as tunable sources for photoluminescence excitation (PLE) spectroscopy. The method was demonstrated in the 720 nm-1070 nm spectral range using a few commercial laser diodes. The samples for PLE measurements were quantum-well structures grown on GaAs and on InP. The method is superior to standard PLE measurements using titanium sapphire laser because it can be extended to any spectral range where anti-reflection coated laser diodes are available.

  2. Photoluminescence excitation measurements using pressure-tuned laser diodes

    International Nuclear Information System (INIS)

    Bercha, Artem; Ivonyak, Yurii; Mędryk, Radosław; Trzeciakowski, Witold A.; Dybała, Filip; Piechal, Bernard

    2015-01-01

    Pressure-tuned laser diodes in external cavity were used as tunable sources for photoluminescence excitation (PLE) spectroscopy. The method was demonstrated in the 720 nm-1070 nm spectral range using a few commercial laser diodes. The samples for PLE measurements were quantum-well structures grown on GaAs and on InP. The method is superior to standard PLE measurements using titanium sapphire laser because it can be extended to any spectral range where anti-reflection coated laser diodes are available

  3. Tapered diode laser pumped 946 nm Nd:YAG laser

    DEFF Research Database (Denmark)

    Cheng, Haynes Pak Hay; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2009-01-01

    We successfully implemented a 946 nm Nd:YAG laser based on a 808 nm tapered diode pump laser. The tapered diode is developed at the Ferdinand-Braun-Institute fur Hochstfrequenztechnik in Germany. Figure 2 shows the experimental setup and results of each pump source coupled into a 1.5 mm crystal...... laser, we show that tapered diode laser pumping potentially increase the power of 946 nm lasers by a factor of two and reduce the threshold by a factor of three....

  4. Use of epitaxial silicon diodes in photon dosimetry

    International Nuclear Information System (INIS)

    Pereira, Lilian Nunes

    2013-01-01

    In this work we report on results obtained with two rad-hard epitaxial (EPI) silicon diodes as on-line dosimeter for diagnostic radiology, mammography and computed tomography, in the 28 kV to 150 kV range. The epitaxial diodes used were processed at University of Hamburg on 50 μm thick epitaxial silicon layer. One sample was not irradiated before using as a dosimeter, while the other received a gamma pre-dose of 200kGy from 60 Co. For comparison, a standard float zone silicon diode was also studied. The samples irradiation was performed using X-ray beams from a Pantak/Seifert generator, model Isovolt 160 HS, previously calibrated with standardized ionization chambers, located at Laboratorio de Calibracao de Instrumentos of IPEN-CNEN/SP. The diode was connected to an electrometer Keithley 6517B in the photovoltaic mode. Irradiations were carried out with the diodes positioned at lm from the X-ray tube (focal spot). The main dosimetric parameters of the EPI samples were evaluated in according to IEC 61674 norm. The calibration coefficients of the diode, in terms of air kerma, were also determined. The repeatability was measured with photon beams of all qualities. The current signals induced showed the diodes are stable, characterized by coefficients of variation less than 0.3%. The current response of the unirradiated EPI diode has been shown to be very linear with dose-rate in the range of 0.8 up to 77.2 mGy/min. A linear relation between charge and dose in the whole energy range was observed for the three samples. It is important to notice that for EPI diodes non energy dependence was observed for mammography beams and until 70kV for radiodiagnostic qualities. The unirradiated diode presented sensitivity higher than the others, showing a decrease of 8% in this parameter after accumulated dose of 49.15 Gy. The dark currents were stable about 0.4 pA during the irradiations, value 10 4 higher than the lowest photocurrents measured. The directional response of both

  5. DFB laser diodes for sensing applications using photoacoustic spectroscopy

    International Nuclear Information System (INIS)

    Koeth, J; Fischer, M; Legge, M; Seufert, J; Roessner, K; Groninga, H

    2010-01-01

    We present typical device characteristics of novel DFB laser diodes which are employed in various sensing applications including high resolution photoacoustic spectroscopy. The laser diodes discussed are based on a genuine fabrication technology which allows for the production of ultra stable devices within a broad spectral range from 760 nm up to 3000 nm wavelength. The devices exhibit narrow linewidths down to <1 MHz which makes them ideally suited for all photoacoustic sensing applications where a high spectral purity is required. As an example we will focus on a typical medical application where these diodes are used for breath analysis using photoacoustic spectroscopy.

  6. Kinetics of current formation in molecular diode

    International Nuclear Information System (INIS)

    Petrov, Eh.G.; Leonov, V.A.; Shevchenko, E.V.

    2012-01-01

    Based on the kinetic theory of election transfer in low-dimensional molecular systems, the formation of transient and stationary currents in a system 'electrode l-molecule-electrode 2' (molecular diode) is studied for different regimes of charge transmission. In the framework of the HOMO-LUMO molecular model, a situation is considered where the current formation is initiated either by molecule photoexcitation or by change of interelectrode voltage bias. It is found that the distant (tunnel) inelastic electron transfer plays a crucial role in changing molecular electronic states and, as a result, in generating transmission channels for hopping (sequential) and distant (direct) current components. The effect of inelastic tunneling is especially pronounced in the condition of resonant electron transmission.

  7. Terahertz optoelectronics with surface plasmon polariton diode.

    Science.gov (United States)

    Vinnakota, Raj K; Genov, Dentcho A

    2014-05-09

    The field of plasmonics has experience a renaissance in recent years by providing a large variety of new physical effects and applications. Surface plasmon polaritons, i.e. the collective electron oscillations at the interface of a metal/semiconductor and a dielectric, may bridge the gap between electronic and photonic devices, provided a fast switching mechanism is identified. Here, we demonstrate a surface plasmon-polariton diode (SPPD) an optoelectronic switch that can operate at exceedingly large signal modulation rates. The SPPD uses heavily doped p-n junction where surface plasmon polaritons propagate at the interface between n and p-type GaAs and can be switched by an external voltage. The devices can operate at transmission modulation higher than 98% and depending on the doping and applied voltage can achieve switching rates of up to 1 THz. The proposed switch is compatible with the current semiconductor fabrication techniques and could lead to nanoscale semiconductor-based optoelectronics.

  8. Characteristics of chirped quantum dot superluminescent diodes

    Energy Technology Data Exchange (ETDEWEB)

    Bae, H.C.; Park, H.L. [Department of Physics, Yonsei University, Seoul 120-749 (Korea); You, Y.C. [Department of Information and Communication Engineering, Sungkyunkwan University, Seoul 440-746 (Korea); Han, I.K. [Nano Device Research Center, Korea Institute of Science and Technology, Seoul 130-650 (Korea); Kim, J.S. [Department of Image System Science and Engineering, Pukyong National University, Pusan Department of Image System Science and Engineering, Pukyong National University, Pusan 608-739 (Korea)

    2009-04-15

    We compared the superluminescent diodes (SLDs) of two types in order to see the effect of embedding another quantum dots (QDs) layer. The insertion of another QDs layer showed a new possibility for a wider spectrum. In addition, through comparing two kinds of SLD structures, the peak positions of the ground state and excited state were observed to be affected differently by band-filling, thermal effect, and the overlap of tails of excited state (ES) gain, according to the wafer structure, and the effect of the cap layer is superior to the carrier non-uniformity. We also revealed the temperature sensitivity of carriers in QDs through measuring characteristic temperature. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Design and evaluation of the XBT diode

    International Nuclear Information System (INIS)

    Wright, E.L.; Vlieks, A.; Fant, K.; Pearson, C.; Koontz, R.; Jensen, D.; Miram, G.

    1993-01-01

    This paper describes the design and experimental results achieved with the 440 kV, microperveance 1.9, XBT (X-band Beam Tester) diode. The Pierce gun was developed for the 100 MW X-band klystron; the high power RF source to be used on the NLC (Next Linear Collider). The gun is electrostatically focused (no magnetic compression) to a beam diameter of 6.35 mm, with an area convergence of 110:1. Maximum cathode loading is approximately 25 A/cm 2 , with a beam power density of 770 MW/cm 2 . The measured beam current was within 2% of the value predicted by simulation with EGUN. Transmission through the highly instrumented beam tester was 99.98%. Some novel techniques were used to achieve near perfect beam transmission, which include the use of a reentrant-floating input pole piece

  10. Flexible IGZO Schottky diodes on paper

    Science.gov (United States)

    Kaczmarski, Jakub; Borysiewicz, Michał A.; Piskorski, Krzysztof; Wzorek, Marek; Kozubal, Maciej; Kamińska, Eliana

    2018-01-01

    With the development of novel device applications, e.g. in the field of robust and recyclable paper electronics, came an increased demand for the understanding and control of IGZO Schottky contact properties. In this work, a fabrication and characterization of flexible Ru-Si-O/IGZO Schottky barriers on paper is presented. It is found that an oxygen-rich atomic composition and microstructure of Ru-Si-O containing randomly oriented Ru inclusions with diameter of 3-5 nm embedded in an amorphous SiO2 matrix are effective in preventing interfacial reactions in the contact region, allowing to avoid pre-treatment of the semiconductor surface and fabricate reliable diodes at room temperature characterized by Schottky barrier height and ideality factor equal 0.79 eV and 2.13, respectively.

  11. Growth and characterization of visible diode lasers

    International Nuclear Information System (INIS)

    Shealy, J.R.; Bour, D.P.

    1988-01-01

    The (Al x Ga 1-x )yIn 1-y rho material system, lattice matched to GaAs substrates, has received much attention for use in visible laser diodes emitting in the spectral region λ--650-680 nm. When lattice matched to GaAs (y=0.5), this alloy spans a direct band gap range from --1.85 eV (at x=0) to --2.3 eV (near the T-X crossover at chi--0.7) It was only recently that device quality epitaxial layers have been prepared in this material due to difficulties with liquid phase epitaxial (LPE) and halide vapor phase epitaxial growth.Only organometallic vapor phase epitaxy (OMVPE) and molecular beam epitaxy (MBE) growth techniques have successfully produced AlGainP laser material

  12. Diode laser welding of aluminum to steel

    International Nuclear Information System (INIS)

    Santo, Loredana; Quadrini, Fabrizio; Trovalusci, Federica

    2011-01-01

    Laser welding of dissimilar materials was carried out by using a high power diode laser to join aluminum to steel in a butt-joint configuration. During testing, the laser scan rate was changed as well as the laser power: at low values of fluence (i.e. the ratio between laser power and scan rate), poor joining was observed; instead at high values of fluence, an excess in the material melting affected the joint integrity. Between these limiting values, a good aesthetics was obtained; further investigations were carried out by means of tensile tests and SEM analyses. Unfortunately, a brittle behavior was observed for all the joints and a maximum rupture stress about 40 MPa was measured. Apart from the formation of intermeltallic phases, poor mechanical performances also depended on the chosen joining configuration, particularly because of the thickness reduction of the seam in comparison with the base material.

  13. Graphite based Schottky diodes formed semiconducting substrates

    Science.gov (United States)

    Schumann, Todd; Tongay, Sefaattin; Hebard, Arthur

    2010-03-01

    We demonstrate the formation of semimetal graphite/semiconductor Schottky barriers where the semiconductor is either silicon (Si), gallium arsenide (GaAs) or 4H-silicon carbide (4H-SiC). The fabrication can be as easy as allowing a dab of graphite paint to air dry on any one of the investigated semiconductors. Near room temperature, the forward-bias diode characteristics are well described by thermionic emission, and the extracted barrier heights, which are confirmed by capacitance voltage measurements, roughly follow the Schottky-Mott relation. Since the outermost layer of the graphite electrode is a single graphene sheet, we expect that graphene/semiconductor barriers will manifest similar behavior.

  14. High efficient white organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, Stefan; Krause, Ralf [Department of Materials Science VI, University of Erlangen-Nuremberg (Germany); Siemens AG, CT MM 1, Erlangen (Germany); Kozlowski, Fryderyk; Schmid, Guenter; Hunze, Arvid [Siemens AG, CT MM 1, Erlangen (Germany); Winnacker, Albrecht [Department of Materials Science VI, University of Erlangen-Nuremberg (Germany)

    2007-07-01

    Due to the rapid progress in the last years the performance of organic light emitting diodes (OLEDs) has reached a level where general lighting presents a most interesting application target. We demonstrate, how the color coordinates of the emission spectrum can be adjusted using a combinatorial evaporation tool to lie on the desired black body curve representing cold and warm white, respectively. The evaluation includes phosphorescent and fluorescent dye approaches to optimize lifetime and efficiency, simultaneously. Detailed results are presented with respect to variation of layer thicknesses and dopant concentrations of each layer within the OLED stack. The most promising approach contains phosphorescent red and green dyes combined with a fluorescent blue one as blue phosphorescent dopants are not yet stable enough to achieve long lifetimes.

  15. Memory Applications Using Resonant Tunneling Diodes

    Science.gov (United States)

    Shieh, Ming-Huei

    Resonant tunneling diodes (RTDs) producing unique folding current-voltage (I-V) characteristics have attracted considerable research attention due to their promising application in signal processing and multi-valued logic. The negative differential resistance of RTDs renders the operating points self-latching and stable. We have proposed a multiple -dimensional multiple-state RTD-based static random-access memory (SRAM) cell in which the number of stable states can significantly be increased to (N + 1)^ m or more for m number of N-peak RTDs connected in series. The proposed cells take advantage of the hysteresis and folding I-V characteristics of RTD. Several cell designs are presented and evaluated. A two-dimensional nine-state memory cell has been implemented and demonstrated by a breadboard circuit using two 2-peak RTDs. The hysteresis phenomenon in a series of RTDs is also further analyzed. The switch model provided in SPICE 3 can be utilized to simulate the hysteretic I-V characteristics of RTDs. A simple macro-circuit is described to model the hysteretic I-V characteristic of RTD for circuit simulation. A new scheme for storing word-wide multiple-bit information very efficiently in a single memory cell using RTDs is proposed. An efficient and inexpensive periphery circuit to read from and write into the cell is also described. Simulation results on the design of a 3-bit memory cell scheme using one-peak RTDs are also presented. Finally, a binary transistor-less memory cell which is only composed of a pair of RTDs and an ordinary rectifier diode is presented and investigated. A simple means for reading and writing information from or into the memory cell is also discussed.

  16. High Intensity Organic Light-emitting Diodes

    Science.gov (United States)

    Qi, Xiangfei

    This thesis is dedicated to the fabrication, modeling, and characterization to achieve high efficiency organic light-emitting diodes (OLEDs) for illumination applications. Compared to conventional lighting sources, OLEDs enabled the direct conversion of electrical energy into light emission and have intrigued the world's lighting designers with the long-lasting, highly efficient illumination. We begin with a brief overview of organic technology, from basic organic semiconductor physics, to its application in optoelectronics, i.e. light-emitting diodes, photovoltaics, photodetectors and thin-film transistors. Due to the importance of phosphorescent materials, we will focus on the photophysics of metal complexes that is central to high efficiency OLED technology, followed by a transient study to examine the radiative decay dynamics in a series of phosphorescent platinum binuclear complexes. The major theme of this thesis is the design and optimization of a novel architecture where individual red, green and blue phosphorescent OLEDs are vertically stacked and electrically interconnected by the compound charge generation layers. We modeled carrier generation from the metal-oxide/doped organic interface based on a thermally assisted tunneling mechanism. The model provides insights to the optimization of a stacked OLED from both electrical and optical point of view. To realize the high intensity white lighting source, the efficient removal of heat is of a particular concern, especially in large-area devices. A fundamental transfer matrix analysis is introduced to predict the thermal properties in the devices. The analysis employs Laplace transforms to determine the response of the system to the combined effects of conduction, convection, and radiation. This perspective of constructing transmission matrices greatly facilitates the calculation of transient coupled heat transfer in a general multi-layer composite. It converts differential equations to algebraic forms, and

  17. All-Quantum-Dot Infrared Light-Emitting Diodes

    KAUST Repository

    Yang, Zhenyu; Voznyy, Oleksandr; Liu, Mengxia; Yuan, Mingjian; Ip, Alexander H.; Ahmed, Osman S.; Levina, Larissa; Kinge, Sachin; Hoogland, Sjoerd; Sargent, Edward H.

    2015-01-01

    © 2015 American Chemical Society. Colloidal quantum dots (CQDs) are promising candidates for infrared electroluminescent devices. To date, CQD-based light-emitting diodes (LEDs) have employed a CQD emission layer sandwiched between carrier transport

  18. Failure Analysis of Heavy-Ion-Irradiated Schottky Diodes

    Science.gov (United States)

    Casey, Megan C.; Lauenstein, Jean-Marie; Wilcox, Edward P.; Topper, Alyson D.; Campola, Michael J.; Label, Kenneth A.

    2017-01-01

    In this work, we use high- and low-magnitude optical microscope images, infrared camera images, and scanning electron microscope images to identify and describe the failure locations in heavy-ion-irradiated Schottky diodes.

  19. Active stabilization of a diode laser injection lock

    Energy Technology Data Exchange (ETDEWEB)

    Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep [Department of Physics, University of Washington, P.O. Box 351560, Seattle, Washington 98195-1560 (United States)

    2016-06-15

    We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser’s transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399 nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.

  20. Active stabilization of a diode laser injection lock.

    Science.gov (United States)

    Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep

    2016-06-01

    We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser's transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399 nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.

  1. 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.

  2. Relativistic properties of spherical diodes with a radial electron flux

    International Nuclear Information System (INIS)

    Chetvertkov, V.I.

    1987-01-01

    Forward and backward electron diodes with concentric spherical electrodes (inner cathode, outer anode or vice versa) are considered under the assumption that the emission is limited by the space charge and the guiding magnetic field is predominantly radial within a region of solid angle α f < 4π bounding the electron flux. The Poisson equations for the relativistic factor γ are solved for generalized model dependences. Ultrarelativistic and new nonrelativistic solutions are found, and analytic approximations to the solution near the cathode are used to carry out numerical calculations. The characteristics of forward and backward diodes turn out to be related to the exact solutions for a planar diode. Accurate approximations are found for calculating the diode parameters in a wide range of voltages; they can also be used to check the validity of the 3/2 laws and the ultrarelativistic solutions

  3. Future Solid State Lighting using LEDs and Diode Lasers

    DEFF Research Database (Denmark)

    Petersen, Paul Michael

    2014-01-01

    applications. Within the coming years, it is expected that the efficiency of blue laser diodes will approach the efficiency of infrared diode lasers. This will enable high efficiency white light generation with very high lumen per watt values. SSL today is mainly based on phosphor converted blue light emitting......Lighting accounts for 20% of all electrical energy usage. Household lighting and commercial lighting such as public and street lighting are responsible for significant greenhouse gas emissions. Therefore, currently many research initiatives focus on the development of new light sources which shows...... significant savings. Solid state lighting (SSL) based on LEDs is today the most efficient light source for generation of high quality white light. Diode lasers, however, have the potential of being more efficient than LEDs for the generation of white light. A major advantage using diode lasers for solid state...

  4. Evaluation of light-emitting diode beacon light fixtures.

    Science.gov (United States)

    2009-12-01

    Rotating beacons containing filament light sources have long been used on highway maintenance trucks : to indicate the presence of the truck to other drivers. Because of advances in light-emitting diode (LED) : technologies, flashing lights containin...

  5. Transcanalicular laser dacryocystorhinostomy using low energy 810 nm diode laser

    Directory of Open Access Journals (Sweden)

    Sanjiv K Gupta

    2012-01-01

    Conclusions: Transcanalicular Laser DCR can be safely performed using a low power 810 nm diode laser. The surgery is elegant, minimally invasive, allows fast rehabilitation, and has an excellent success rate.

  6. Fabrication of organic light emitting diode using Molybdenum ...

    Indian Academy of Sciences (India)

    65

    out by measuring sheet resistance, optical transmittance and surface ... role in the organic light-emitting diode (OLED) performance because it determines the .... coated glass by thermal vacuum deposition method and optimize it by using ...

  7. Overview on new diode lasers for defense applications

    Science.gov (United States)

    Neukum, Joerg

    2012-11-01

    Diode lasers have a broad wavelength range, from the visible to beyond 2.2μm. This allows for various applications in the defense sector, ranging from classic pumping of DPSSL in range finders or target designators, up to pumping directed energy weapons in the 50+ kW range. Also direct diode applications for illumination above 1.55μm, or direct IR countermeasures are of interest. Here an overview is given on some new wavelengths and applications which are recently under discussion. In this overview the following aspects are reviewed: • High Power CW pumps at 808 / 880 / 940nm • Pumps for DPAL - Diode Pumped Alkali Lasers • High Power Diode Lasers in the range market.

  8. Active stabilization of a diode laser injection lock

    International Nuclear Information System (INIS)

    Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep

    2016-01-01

    We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser’s transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399 nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.

  9. Simplified atom trap using a single microwave modulated diode laser

    International Nuclear Information System (INIS)

    Newbury, N.R.; Myatt, C.J.; Wieman, C.E.

    1993-01-01

    We have demonstrated microwave modulation of a diode laser which is operated with optical feedback from a diffraction grating. By directly modulating the diode laser current at frequencies up to 6.8 GHz, we observed 2-30% of the laser power in a single sideband for 20mW of microwave power. Using such a diode laser modulated at 6.6GHz, we have trapped 87 Rb in a vapor cell. With 10mW of microwave power, the number of trapped atoms was only 15% smaller than the number obtained using two lasers in the conventional manner. A microwave modulated diode laser should also be useful for driving stimulated Raman transitions between the hyperfine levels of Rb or Cs

  10. Diode Laser Raman Scattering Prototype Gas-Phase Environmental Monitoring

    National Research Council Canada - National Science Library

    Benner, Robert

    1999-01-01

    We proposed developing a diode-laser-based, full spectrum Raman scattering instrument incorporating a multipass, external cavity enhancement cell for full spectrum, gas phase analysis of environmental pollutants...

  11. Durability of PEDOT: PSS-pentacene Schottky diode

    International Nuclear Information System (INIS)

    Kang, K S; Lim, H K; Cho, K Y; Han, K J; Kim, Jaehwan

    2008-01-01

    The durability and failure cause of a polymer Schottky diode made with PEDOT : PSS-pentacene were investigated. A polymer Schottky diode was fabricated by dissolving pentacene in N-methylpyrrolidone (NMP) and mixing with PEDOT : PSS. Pentacene solution having a maximum concentration of approximately 9.7 mmoles was prepared by simply stirring the solution at room temperature for 36 h. As the pentacene concentration increased, the absorption of the broad UV regime increased dramatically. However, absorption peaks of pentacene at 301 and 260 nm were not observed for the PEDOT : PSS-pentacene. A three-layered polymer Schottky diode was fabricated and its current-voltage (I-V) characteristic was evaluated. The current was reduced by 7% in the first 50 min and then stabilized during biased electrical field sweeps. After 500 and 800 min, catastrophic failure occurred. FESEM images revealed that the electrode damage caused catastrophic failure of the Schottky diode. (fast track communication)

  12. Wavelength stabilized multi-kW diode laser systems

    Science.gov (United States)

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

    2015-03-01

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

  13. Organic light emitting diode with surface modification layer

    Science.gov (United States)

    Basil, John D.; Bhandari, Abhinav; Buhay, Harry; Arbab, Mehran; Marietti, Gary J.

    2017-09-12

    An organic light emitting diode (10) includes a substrate (12) having a first surface (14) and a second surface (16), a first electrode (32), and a second electrode (38). An emissive layer (36) is located between the first electrode (32) and the second electrode (38). The organic light emitting diode (10) further includes a surface modification layer (18). The surface modification layer (18) includes a non-planar surface (30, 52).

  14. Organic light emitting diode with light extracting electrode

    Energy Technology Data Exchange (ETDEWEB)

    Bhandari, Abhinav; Buhay, Harry

    2017-04-18

    An organic light emitting diode (10) includes a substrate (20), a first electrode (12), an emissive active stack (14), and a second electrode (18). At least one of the first and second electrodes (12, 18) is a light extracting electrode (26) having a metallic layer (28). The metallic layer (28) includes light scattering features (29) on and/or in the metallic layer (28). The light extracting features (29) increase light extraction from the organic light emitting diode (10).

  15. Study of relativistic electron beams generated by a foilless diode

    International Nuclear Information System (INIS)

    Jones, M.E.; Thode, L.E.

    1979-01-01

    Preliminary results of a numerical and analytical study of foilless diodes are presented. The work produced an electron emission algorithm for the particle-in-cell simulation code CCUBE. Diode performance was studied as a function of applied magnetic field strength and simple geometry changes. Annular electron beams with an energy of 5 MeV appear obtainable with densities exceeding 10 14 cm -3 . 8 figures

  16. Active Stabilization of a Diode Laser Injection Lock

    OpenAIRE

    Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep

    2016-01-01

    We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser's transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudde...

  17. Ion diode diagnostics to resolve beam quality issues

    Energy Technology Data Exchange (ETDEWEB)

    Bluhm, H; Buth, L; Hoppe, P [Forschungszentrum Karlsruhe (Germany). Institut fuer Neutronenphysik und Reaktortechnik; and others

    1997-12-31

    Various diagnostic methods and instruments are under development at the Forschungszentrum Karlsruhe to measure important physical quantities in the accelerating gap of high power diodes on KALIF with a high spatial and temporal resolution. The methods include optical spectroscopy, refractive index measurements, dispersion interferometry, and high resolution energy analysis. The setup of these diagnostic tools and the first results obtained for applied and self-magnetically insulated diodes are presented. (author). 6 figs., 5 refs.

  18. Impedance characteristics of the Bz diode on the LION accelerator

    International Nuclear Information System (INIS)

    Meyerhofer, D.D.; Horioka, K.; Kusse, B.; Rondeau, G.; Struckman, C.

    1987-01-01

    The LION accelerator at Cornell University is being used to study the characteristics of the applied B/sub z/, or 'barrel' diode. This 0.8 TW, 4 ohm, ion accelerator has the ability to take several shots per day, and hence alloys systematic scans to be performed. An important result of a recent series of experiments is that the diode impedance remains relatively constant, decaying only slowly, during the 50 nsec pulse. When the diode is operated with a 4.5 mm gap and a 21 kG insulating magnetic field, the typical diode parameters, are a voltage of 1 MV and a total current of 250 kA, leading to a diode impedance of 4 ohms and power of 0.25 TW. The diode impedance decays with a 100 nsec time constant. The ion beams have peak currents of roughly 125 kA and typical impedances of Bohms, which decays with a time constant of 25 nsec. The Child-Langmuir gap was approximately 2 mm and closed with a velocity of roughly 2X10/sup 6/ cm/sec. Current experimental work is aimed at characterizing the impedance of the B/sub z/ diode as a function of the applied magnetic field, the A-K gap, the anode curvature, and the anode groove parameters. In addition, the effect of changing the voltage rise with a plasma opening switch and of adding an electron limiter is examined. The ion beam quality is examined at the focus of the barrel diode with a swept Thomson parabola and various Rutherford scattering diagnostics

  19. Particle beam dynamics in a magnetically insulated coaxial diode

    International Nuclear Information System (INIS)

    Korenev, V.G.; Magda, I.I.; Sinitsin, V.G.

    2015-01-01

    The dynamics of charged particle beams emitted from a cathode into a smooth coaxial diode with magnetic insulation is studied with the aid of 3-D PIC simulation. The processes controlling space charge formation and its evolution in the diode are modeled for geometries typical of high-voltage millimeter wave magnetrons that are characterized by very high values of emission currents, hence high space charge densities.

  20. Laser diodes for sensing applications: adaptive cruise control and more

    Science.gov (United States)

    Heerlein, Joerg; Morgott, Stefan; Ferstl, Christian

    2005-02-01

    Adaptive Cruise Controls (ACC) and pre-crash sensors require an intelligent eye which can recognize traffic situations and deliver a 3-dimensional view. Both microwave RADAR and "Light RADAR" (LIDAR) systems are well suited as sensors. In order to utilize the advantages of LIDARs -- such as lower cost, simpler assembly and high reliability -- the key component, the laser diode, is of primary importance. Here, we present laser diodes which meet the requirements of the automotive industry.

  1. Spectral beam combining of diode lasers with high efficiency

    DEFF Research Database (Denmark)

    Müller, André; Vijayakumar, Deepak; Jensen, Ole Bjarlin

    2012-01-01

    Based on spectral beam combining we obtain 16 W of output power, combining two 1063 nm DBR-tapered diode lasers. The spectral separation within the combined beam can be used for subsequent sum-frequency generation.......Based on spectral beam combining we obtain 16 W of output power, combining two 1063 nm DBR-tapered diode lasers. The spectral separation within the combined beam can be used for subsequent sum-frequency generation....

  2. Transurethral vaporesection of prostate: diode laser or thulium laser?

    Science.gov (United States)

    Tan, Xinji; Zhang, Xiaobo; Li, Dongjie; Chen, Xiong; Dai, Yuanqing; Gu, Jie; Chen, Mingquan; Hu, Sheng; Bai, Yao; Ning, Yu

    2018-05-01

    This study compared the safety and effectiveness of the diode laser and thulium laser during prostate transurethral vaporesection for treating benign prostate hyperplasia (BPH). We retrospectively analyzed 205 patients with BPH who underwent a diode laser or thulium laser technique for prostate transurethral vaporesection from June 2016 to June 2017 and who were followed up for 3 months. Baseline characteristics of the patients, perioperative data, postoperative outcomes, and complications were compared. We also assessed the International Prostate Symptom Score (IPSS), quality of life (QoL), maximum flow rate (Q max ), average flow rate (AFR), and postvoid residual volume (PVR) at 1 and 3 months postoperatively to evaluate the functional improvement of each group. There were no significant differences between the diode laser and thulium laser groups related to age, prostate volume, operative time, postoperative hospital stays, hospitalization costs, or perioperative data. The catheterization time was 3.5 ± 0.8 days for the diode laser group and 4.7 ± 1.8 days for the thulium laser group (p diode laser and thulium laser contributes to safe, effective transurethral vaporesection in patients with symptomatic BPH. Diode laser, however, is better than thulium laser for prostate transurethral vaporesection because of its shorter catheterization time. The choice of surgical approach is more important than the choice of laser types during clinical decision making for transurethral laser prostatectomy.

  3. Radiation resistant quench protection diodes for the LHC

    International Nuclear Information System (INIS)

    Hagedorn, D.; Coull, L.

    1994-01-01

    The quench protection diodes for the proposed Large Hadron Collider at CERN will be located inside the He-II vessel of the short straight section of one half cell, where they could be exposed to a radiation dose of about 50 kGy and a total neutron fluence of about 10 15 n/cm 2 over 10 years at temperatures of about 2 K. To investigate the influence of irradiation on the electrical characteristics of the diodes, newly developed diodes of thin base region of the diffusion type and of the epitaxial type have been submitted to irradiation tests at liquid nitrogen temperature in a target area of the SPS accelerator at CERN. The degradation of the electrical characteristics of the diodes for a radiation dose up to about 20 kGy and neutron fluence of up to about 5 10 14 n/cm 2 and the effect of carrier injection and thermal annealing after irradiation have been measured. The test results show that only the thin base diodes of the epitaxial type are really radiation resistant. A compromise must be found between required blocking characteristics and radiation resistance. Annealing by carrier injection and occasional warm up to room temperature can extend the service life of irradiated diodes quite substantially

  4. Microclump effects in magnetically-immersed electron diodes

    International Nuclear Information System (INIS)

    Olson, C.L.

    1998-01-01

    Magnetically-immersed electron diodes are being developed to produce needle-like, high-current, electron beams for radiography applications. An immersed diode consists of a needle cathode and a planar anode/bremmstrahlung converter which are both immersed in a strong solenoidal magnetic field (12--50 T); nominal parameters are 10 MV, 40 kA, 0.5 mm radius cathode, and 5--35 cm anode-cathode gaps. A physical picture of normal and abnormal diode behavior is emerging. Normal diode behavior occurs for times 0 ≤ t ≤ τ, where the transition time τ is typically 30 ns; during this time, bipolar space-charge limited flow occurs, which scales well to desired radiography parameters of high dose and small spot size. Abnormal diode behavior occurs for t ≥ τ, which results in substantial increases in spot size and current (impedance reduction). This abnormal behavior appears to be caused by an increase in ion charge in the gap, which may result from poor vacuum, impurity ions undergoing ion-ion stripping collisions during transit, or microclumps undergoing stripping collisions during transit. The potential effects of microclumps on diode behavior are reported here

  5. High Power High Efficiency Diode Laser Stack for Processing

    Science.gov (United States)

    Gu, Yuanyuan; Lu, Hui; Fu, Yueming; Cui, Yan

    2018-03-01

    High-power diode lasers based on GaAs semiconductor bars are well established as reliable and highly efficient laser sources. As diode laser is simple in structure, small size, longer life expectancy with the advantages of low prices, it is widely used in the industry processing, such as heat treating, welding, hardening, cladding and so on. Respectively, diode laser could make it possible to establish the practical application because of rectangular beam patterns which are suitable to make fine bead with less power. At this power level, it can have many important applications, such as surgery, welding of polymers, soldering, coatings and surface treatment of metals. But there are some applications, which require much higher power and brightness, e.g. hardening, key hole welding, cutting and metal welding. In addition, High power diode lasers in the military field also have important applications. So all developed countries have attached great importance to high-power diode laser system and its applications. This is mainly due their low performance. In this paper we will introduce the structure and the principle of the high power diode stack.

  6. High-performance noncontact thermal diode via asymmetric nanostructures

    Science.gov (United States)

    Shen, Jiadong; Liu, Xianglei; He, Huan; Wu, Weitao; Liu, Baoan

    2018-05-01

    Electric diodes, though laying the foundation of modern electronics and information processing industries, suffer from ineffectiveness and even failure at high temperatures. Thermal diodes are promising alternatives to relieve above limitations, but usually possess low rectification ratios, and how to obtain a high-performance thermal rectification effect is still an open question. This paper proposes an efficient contactless thermal diode based on the near-field thermal radiation of asymmetric doped silicon nanostructures. The rectification ratio computed via exact scattering theories is demonstrated to be as high as 10 at a nanoscale gap distance and period, outperforming the counterpart flat-plate diode by more than one order of magnitude. This extraordinary performance mainly lies in the higher forward and lower reverse radiative heat flux within the low frequency band compared with the counterpart flat-plate diode, which is caused by a lower loss and smaller cut-off wavevector of nanostructures for the forward and reversed scheme, respectively. This work opens new routes to realize high performance thermal diodes, and may have wide applications in efficient thermal computing, thermal information processing, and thermal management.

  7. Quaternary InGaAsSb Thermophotovoltaic Diode Technology

    International Nuclear Information System (INIS)

    M Dashiell; J Beausang; H Ehsani; G Nichols; D DePoy; L Danielson; P Talamo; K Rahner; E Brown; S Burger; P Fourspring; W Topper; P Baldasaro; C Wang; R Huang; M Connors; G Turner; Z Shellenbarger; G Taylor; Jizhong Li; R Martinelli; D Donetski; S Anikeev; G Belenky; S Luryl

    2005-01-01

    Thermophotovoltaic (TPV) diodes fabricated from InGaAsSb alloys lattice-matched to GaSb substrates are grown by Metal Organic Vapor Phase Epitaxy (MOVPE). 0.53eV InGaAsSb TPV diodes utilizing front-surface spectral control filters have been tested in a vacuum cavity and a TPV thermal-to-electric conversion efficiency (η TPV ) and a power density (PD) of η TPV = 19% and PD=0.58 W/cm 2 were measured for T radiator = 950 C and T diode = 27 C. Recombination coefficients deduced from minority carrier measurements and the theory reviewed in this article predict a practical limit to the maximum achievable conversion efficiency and power density for 0.53eV InGaAsSb TPV. The limits for the above operating temperatures are projected to be η TPV = 26% and PD = 0.75 W/cm 2 . These limits are extended to η TPV = 30% and PD = 0.85W/cm 2 if the diode active region is bounded by a reflective back surface to enable photon recycling and a two-pass optical path length. The internal quantum efficiency of the InGaAsSb TPV diode is close to the theoretically predicted limits, with the exception of short wavelength absorption in GaSb contact layers. Experiments show that the open circuit voltage of the 0.53eV InGaAsSb TPV diodes is not strongly dependent on the device architectures studied in this work where both N/P and P/N double heterostructure diodes have been grown with various acceptor and donor doping levels, having GaSb and AlGaAsSb confinement, and also partial back surface reflectors. Lattice matched InGaAsSb TPV diodes were fabricated with bandgaps ranging from 0.6 to 0.5eV without significant degradation of the open circuit voltage factor, quantum efficiency, or fill factor as the composition approached the miscibility gap. The key diode performance parameter which is limiting efficiency and power density below the theoretical limits in InGaAsSb TPV devices is the open circuit voltage. The open circuit voltages of state-of-the-art 0.53eV InGaAsSb TPV diode are ∼10

  8. Anode plasma and focusing reb diodes

    International Nuclear Information System (INIS)

    Goldstein, S.A.; Swain, D.W.; Hadley, G.R.; Mix, L.P.

    1975-01-01

    The use of electrical, optical, x-ray, and particle diagnostics to characterize the production of anode plasma and to monitor its influence on beam generation and focusing is reviewed. Studies using the Nereus accelerator show that after cathode turn-on, deposition of several kJ/gm on the anode is necessary before ions from hydrocarbons, adsorbed gases, and heavier metallic species are detected. The actual time at which ions are liberated depends on several factors, one of which is the specific heat of the anode substrate. Once formed, anode ions cross the A-K gap (with an energy equal to the diode voltage) and interact with the cathode to produce an axially peaked beam profile, a ''pinch'' which does not follow the critical current criterion. Experiments with externally generated anode plasma show that this type of pinch can be attracted to localized areas on the anode. Preliminary observations on Hydra indicate the anode plasma composition is similar to that on Nereus. The effect of this plasma on pinch dynamics currently is under investigation

  9. High power diode laser remelting of metals

    International Nuclear Information System (INIS)

    Chmelickova, H; Tomastik, J; Ctvrtlik, R; Supik, J; Nemecek, S; Misek, M

    2014-01-01

    This article is focused on the laser surface remelting of the steel samples with predefined overlapping of the laser spots. The goal of our experimental work was to evaluate microstructure and hardness both in overlapped zone and single pass ones for three kinds of ferrous metals with different content of carbon, cast iron, non-alloy structural steel and tool steel. High power fibre coupled diode laser Laserline LDF 3600-100 was used with robotic guided processing head equipped by the laser beam homogenizer that creates rectangular beam shape with uniform intensity distribution. Each sample was treated with identical process parameters - laser power, beam diameter, focus position, speed of motion and 40% spot overlap. Dimensions and structures of the remelted zone, zone of the partial melting, heat affected zone and base material were detected and measured by means of laser scanning and optical microscopes. Hardness progress in the vertical axis of the overlapped zone from remelted surface layer to base material was measured and compared with the hardness of the single spots. The most hardness growth was found for cast iron, the least for structural steel. Experiment results will be used to processing parameters optimization for each tested material separately.

  10. 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.

  11. High-power pure blue laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, M.; Ohizumi, Y.; Hoshina, Y.; Tanaka, T.; Yabuki, Y.; Goto, S.; Ikeda, M. [Development Center, Sony Shiroishi Semiconductor Inc., Miyagi (Japan); Funato, K. [Materials Laboratories, Sony Corporation, Kanagawa (Japan); Tomiya, S. [Materials Analysis Laboratory, Sony Corporation, Kanagawa (Japan)

    2007-06-15

    We successfully developed high-power and long-lived pure blue laser diodes (LDs) having an emission wavelength of 440-450 nm. The pure-blue LDs were grown by metalorganic chemical vapor deposition (MOCVD) on GaN substrates. The dislocation density was successfully reduced to {proportional_to}10{sup 6} cm{sup -2} by optimizing the MOCVD growth conditions and the active layer structure. The vertical layer structure was designed to have an absorption loss of 4.9 cm{sup -1} and an internal quantum efficiency of 91%. We also reduced the operating current density to 6 kA/cm{sup 2} under 750 mW continuous-wave operation at 35 C by optimizing the stripe width to 12 {mu}m and the cavity length to 2000 {mu}m. The half lifetimes in constant current mode are estimated to be longer than 10000 h. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Power saving regulated light emitting diode circuit

    International Nuclear Information System (INIS)

    Haville, G. D.

    1985-01-01

    A power saving regulated light source circuit, comprising a light emitting diode (LED), a direct current source and a switching transistor connected in series with the LED, a control voltage producing resistor connected in series with the LED to produce a control voltage corresponding to the current through the LED, a storage capacitor connected in parallel with the series combination of the LED and the resistor, a comparator having its output connected to the input of the transistor, the comparator having a reference input and a control input, a stabilized biasing source for supplying a stabilized reference voltage to the reference input, the control input of the comparator being connected to the control voltage producing resistor, the comparator having a high output state when the reference voltage exceeds the control voltage while having a low output state when the control voltage exceeds the reference voltage, the transistor being conductive in response to the high state while being nonconductive in response to the low state, the transistor when conductive being effective to charge the capacitor and to increase the control voltage, whereby the comparator is cycled between the high and low output states while the transistor is cycled between conductive and nonconductive states

  13. Aggregation in organic light emitting diodes

    Science.gov (United States)

    Meyer, Abigail

    Organic light emitting diode (OLED) technology has great potential for becoming a solid state lighting source. However, there are inefficiencies in OLED devices that need to be understood. Since these inefficiencies occur on a nanometer scale there is a need for structural data on this length scale in three dimensions which has been unattainable until now. Local Electron Atom Probe (LEAP), a specific implementation of Atom Probe Tomography (APT), is used in this work to acquire morphology data in three dimensions on a nanometer scale with much better chemical resolution than is previously seen. Before analyzing LEAP data, simulations were used to investigate how detector efficiency, sample size and cluster size affect data analysis which is done using radial distribution functions (RDFs). Data is reconstructed using the LEAP software which provides mass and position data. Two samples were then analyzed, 3% DCM2 in C60 and 2% DCM2 in Alq3. Analysis of both samples indicated little to no clustering was present in this system.

  14. Silicon Diode Dosimeter for Fast Neutrons

    International Nuclear Information System (INIS)

    Svansson, L.; Widell, C.O.; Swedberg, P.; Wik, M.

    1968-11-01

    The change of the current-voltage characteristics of a small silicon diode is used as a measure of fast neutron dose in the Fast Neutron Dosimeter 5422. This change is permanent and therefore it is possible to integrate doses over a long period of time. Doses from some rad up to 1000 rad can be measured and the information stored is not destroyed during readout. Considerable research work in this field has previously been carried out by the Swedish Institute for National Defence in collaboration with the Institute of Semiconductor Research Stockholm. The present investigation has been made in order to establish the possibilities of the dosimeter for practical applications and to study the variations of important parameters as a function of the production process. In particular the following parameters have been studied: - dose sensitivity, - energy dependence; - fading effect; - temperature influence; - maximum measurable dose. In general one might conclude that the dosimeter 5422 well fulfills requirements usually specified for a dosimeter for field service. Temperature influence and fading effect are of little practical importance within the recommended range of measurement

  15. Silicon Diode Dosimeter for Fast Neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Svansson, L; Widell, C O; Swedberg, P [The Inst. of Semiconductor Researc h, Stockholm (Sweden); Wik, M [The Swedish Institute for National Defence, Sun dbyberg (Sweden)

    1968-11-15

    The change of the current-voltage characteristics of a small silicon diode is used as a measure of fast neutron dose in the Fast Neutron Dosimeter 5422. This change is permanent and therefore it is possible to integrate doses over a long period of time. Doses from some rad up to 1000 rad can be measured and the information stored is not destroyed during readout. Considerable research work in this field has previously been carried out by the Swedish Institute for National Defence in collaboration with the Institute of Semiconductor Research Stockholm. The present investigation has been made in order to establish the possibilities of the dosimeter for practical applications and to study the variations of important parameters as a function of the production process. In particular the following parameters have been studied: - dose sensitivity, - energy dependence; - fading effect; - temperature influence; - maximum measurable dose. In general one might conclude that the dosimeter 5422 well fulfills requirements usually specified for a dosimeter for field service. Temperature influence and fading effect are of little practical importance within the recommended range of measurement.

  16. Micropulse diode laser trabeculoplasty -- 180-degree treatment.

    Science.gov (United States)

    Rantala, Elina; Välimäki, Juha

    2012-08-01

    To evaluate the outcome of 180° micropulse diode laser trabeculoplasty (MDLT) in patients with open-angle glaucoma. A retrospective review of 40 eyes of 29 MDLT-treated patients with a minimum follow-up time of 6 months. Successful outcome was defined as follows: (i) a ≥20% or (ii) a ≥3-mmHg decrease of intraocular pressure (IOP), no further need for laser- or incisional surgery and the number of glaucoma medication was the same or less than preoperative. These definitions will from now on be referred to as definition one and definition two. Life-table analysis showed an overall success rate of 2.5% (1/40) and 7.5% (3/40) (according to definitions one and two, respectively) after up to 19 months of follow-up. The average time for failure was by definition one 2.9 months (standard deviation, SD ± 3.5, range 1-12 months) and by definition two 3.3 months (SD ± 3.9, range 1-16 months). There were no intra- or postoperative complications caused by MDLT. Postoperative inflammatory reaction, cells and flare, was scanty. Our results suggest that 180° MDLT is a safe but ineffective treatment in patients with open-angle glaucoma. © 2010 The Authors. Acta Ophthalmologica © 2010 Acta Ophthalmologica Scandinavica Foundation.

  17. Coherence characteristics of light-emitting diodes

    International Nuclear Information System (INIS)

    Mehta, Dalip Singh; Saxena, Kanchan; Dubey, Satish Kumar; Shakher, Chandra

    2010-01-01

    We report the measurement of coherence characteristics of light-emitting diodes (LEDs). Experiments were performed using red and green color LEDs directly illuminating the Young's double slit kept in the far-zone. Fourier transform fringe analysis technique was used for the measurement of the visibility of interference fringes from which the modulus of degree of spectral coherence was determined. Low degree of spectral coherence, typically 0.4 for red and 0.2 for green LED with double-slit separation of 400 μm was observed. A variable slit was then kept in front of the LEDs and the double slit was illuminated with the light coming out of the slit. Experiments were performed with various slit sizes and the visibility of the interference fringes was observed. It was found that visibility of the interference fringes changes drastically in presence of variable slit kept in front of LEDs and a high degree of spectral coherence, typically 0.85 for red and 0.8 for green LED with double-slit separation of 400 μm and rectangular slit opening of 500 μm was observed. The experimental results are compared with the theoretical counterparts. Coherence lengths of both the LEDs were also determined and it was obtained 5.8±2 and 24±4 μm for green and red LEDs, respectively.

  18. Diode laser for abdominal tissue cauterization

    Science.gov (United States)

    Durville, Frederic M.; Rediker, Robert H.; Connolly, Raymond J.; Schwaitzberg, Steven D.; Lantis, John

    1999-06-01

    We have developed a new device to effectively and quickly stop bleeding. The new device uses a small, 5 W diode laser to heat-up the tip of a modified medical forceps. The laser beam is totally contained within a protective enclosure, satisfying the requirements for a Class I laser system, which eliminates the need to protective eyewear. The new device is used in a manner similar to that of a bipolar electrocautery device. After visual location, the bleeding site or local vessel(s) is grabbed and clamped with the tips of the forceps-like instrument. The laser is then activated for a duration of typically 5 sec or until traditional visual or auditory clues such as local blubbling and popping indicate that the targeted site is effectively cauterized. When the laser is activated, the tip of the instrument, thus providing hemostasis. The new device was evaluated in animal models and compared with the monopolar and bipolar electrocautery, and also with the recently developed ultrasound technology. It has new been in clinical trials for abdominal surgery since September 1997.

  19. Crosstalk of HgCdTe LWIR n-on-p diode arrays

    International Nuclear Information System (INIS)

    Sun Yinghui; Zhang Bo; Yu Meifang; Liao Qingjun; Zhang Yan; Wen Xin; Jiang Peilu; Hu Xiaoning; Dai Ning

    2009-01-01

    Crosstalk of HgCdTe long-wavelength infrared (LWIR) n-on-p diode arrays was measured using scanning laser microscopy. During the measurement, HgCdTe diode arrays with different diode pitches were frontside illuminated by a He-Ne laser at liquid nitrogen temperature and room temperature. The experimental results show that crosstalk between the nearest neighboring diodes decreases exponentially as the diode pitch increases, and the factors that affect the obtained crosstalk are presented and analyzed. Crosstalk out of the nominal diode area (optically sensitive area) is also measured and discussed.

  20. 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.

  1. In vivo dosimetry with silicon diodes in total body irradiation

    International Nuclear Information System (INIS)

    Oliveira, F.F.; Amaral, L.L.; Costa, A.M.; Netto, T.G.

    2014-01-01

    The aim of this work is the characterization and application of silicon diode detectors for in vivo dosimetry in total body irradiation (TBI) treatments. It was evaluated the diode response with temperature, dose rate, gantry angulations and field size. A maximum response variation of 2.2% was obtained for temperature dependence. The response variation for dose rate and angular was within 1.2%. For field size dependence, the detector response increased with field until reach a saturation region, where no more primary radiation beam contributes for dose. The calibration was performed in a TBI setup. Different lateral thicknesses from one patient were simulated and then the calibration factors were determined by means of maximum depth dose readings. Subsequent to calibration, in vivo dosimetry measurements were performed. The response difference between diode readings and the prescribed dose for all treatments was below 4%. This difference is in agreement as recommended by the International Commission on Radiation Units and Measurements (ICRU), which is ±5%. The present work to test the applicability of a silicon diode dosimetry system for performing in vivo dose measurements in TBI techniques presented good results. These measurements demonstrated the value of diode dosimetry as a treatment verification method and its applicability as a part of a quality assurance program in TBI treatments. - Highlights: ► Characterization of a silicon diode dosimetry system. ► Application of the diodes for in vivo dosimetry in total body irradiation treatments. ► Implementation of in vivo dosimetry as a part of a quality assurance program in radiotherapy

  2. Disruptive laser diode source for embedded LIDAR sensors

    Science.gov (United States)

    Canal, Celine; Laugustin, Arnaud; Kohl, Andreas; Rabot, Olivier

    2017-02-01

    Active imaging based on laser illumination is used in various fields such as medicine, security, defense, civil engineering and in the automotive sector. In this last domain, research and development to bring autonomous vehicles on the roads has been intensified these last years with an emphasis on lidar technology that is probably the key to achieve full automation level. Based on time-of-flight measurements, the profile of objects can be measured together with their location in various conditions, creating a 3D mapping of the environment. To be embedded on a vehicle as advanced driver assistance systems (ADAS), these sensors require compactness, low-cost and reliability, as it is provided by a flash lidar. An attractive candidate, especially with respect to cost reduction, for the laser source integrated in these devices is certainly laser diodes as long as they can provide sufficiently short pulses with a high energy. A recent breakthrough in laser diode and diode driver technology made by Quantel (Les Ulis, France) now allows laser emission higher than 1 mJ with pulses as short as 12 ns in a footprint of 4x5 cm2 (including both the laser diode and driver) and an electrical-to-optical conversion efficiency of the whole laser diode source higher than 25% at this level of energy. The components used for the laser source presented here can all be manufactured at low cost. In particular, instead of having several individual laser diodes positioned side by side, the laser diodes are monolithically integrated on a single semiconductor chip. The chips are then integrated directly on the driver board in a single assembly step. These laser sources emit in the range of 800-1000 nm and their emission is considered to be eye safe when taking into account the high divergence of the output beam and the aperture of possible macro lenses so that they can be used for end consumer applications. Experimental characterization of these state-of-the-art pulsed laser diode sources

  3. Application of AXUV diode detectors at ASDEX Upgrade

    Science.gov (United States)

    Bernert, M.; Eich, T.; Burckhart, A.; Fuchs, J. C.; Giannone, L.; Kallenbach, A.; McDermott, R. M.; Sieglin, B.

    2014-03-01

    In the ASDEX Upgrade tokamak, a radiation measurement for a wide spectral range, based on semiconductor detectors, with 256 lines of sight and a time resolution of 5μs was recently installed. In combination with the foil based bolometry, it is now possible to estimate the absolutely calibrated radiated power of the plasma on fast timescales. This work introduces this diagnostic based on AXUV (Absolute eXtended UltraViolet) n-on-p diodes made by International Radiation Detectors, Inc. The measurement and the degradation of the diodes in a tokamak environment is shown. Even though the AXUV diodes are developed to have a constant sensitivity for all photon energies (1 eV-8 keV), degradation leads to a photon energy dependence of the sensitivity. The foil bolometry, which is restricted to a time resolution of less than 1 kHz, offers a basis for a time dependent calibration of the diodes. The measurements of the quasi-calibrated diodes are compared with the foil bolometry and found to be accurate on the kHz time scale. Therefore, it is assumed, that the corrected values are also valid for the highest time resolution (200 kHz). With this improved diagnostic setup, the radiation induced by edge localized modes is analyzed on fast timescales.

  4. Application of AXUV diode detectors at ASDEX Upgrade

    International Nuclear Information System (INIS)

    Bernert, M.; Eich, T.; Burckhart, A.; Fuchs, J. C.; Giannone, L.; Kallenbach, A.; McDermott, R. M.; Sieglin, B.

    2014-01-01

    In the ASDEX Upgrade tokamak, a radiation measurement for a wide spectral range, based on semiconductor detectors, with 256 lines of sight and a time resolution of 5μs was recently installed. In combination with the foil based bolometry, it is now possible to estimate the absolutely calibrated radiated power of the plasma on fast timescales. This work introduces this diagnostic based on AXUV (Absolute eXtended UltraViolet) n-on-p diodes made by International Radiation Detectors, Inc. The measurement and the degradation of the diodes in a tokamak environment is shown. Even though the AXUV diodes are developed to have a constant sensitivity for all photon energies (1 eV-8 keV), degradation leads to a photon energy dependence of the sensitivity. The foil bolometry, which is restricted to a time resolution of less than 1 kHz, offers a basis for a time dependent calibration of the diodes. The measurements of the quasi-calibrated diodes are compared with the foil bolometry and found to be accurate on the kHz time scale. Therefore, it is assumed, that the corrected values are also valid for the highest time resolution (200 kHz). With this improved diagnostic setup, the radiation induced by edge localized modes is analyzed on fast timescales

  5. Ampfion-hybrid diode on the Cornell LION accelerator

    International Nuclear Information System (INIS)

    Rondeau, G.D.; Greenly, J.B.; Hammer, D.A.

    1984-01-01

    An ampfion hybrid diode, previously run on the HYDRAMITE accelerator at Sandia National Laboratories has recently been installed on the Cornell LION accelerator (1 TW, 1.8 MV, 40 ns pulse). The ampfion hybrid diode is magnetically insulated by means of a field coil in series with the cathode structure of the diode. An epoxy dielectric flashboard on the anode provides an anode plasma to supply the extracted ions. The diode has a geometric focal length of 20 cm. The experiment is equipped with plasma erosion opening switches on the anode stock to eliminate prepulse and improve the generator voltage risetime. Diagnostics include magnetic pickup loops to measure currents in the diode structure and non-neutral beam currents, biased charge collectors, and damage targets. An alpha particle pin hole camera utilizing the p,α reaction of fast (>500 kV) protons on boron or lithium is being developed to measure focus quality and proton current. Plastic track detector will be used to image the alpha particles coming from a boron or lithium target. A second pin hole camera uses a plastic scintillator and light detector to give time resolved focused ion intensity

  6. Simulations of Large-Area Electron Beam Diodes

    Science.gov (United States)

    Swanekamp, S. B.; Friedman, M.; Ludeking, L.; Smithe, D.; Obenschain, S. P.

    1999-11-01

    Large area electron beam diodes are typically used to pump the amplifiers of KrF lasers. Simulations of large-area electron beam diodes using the particle-in-cell code MAGIC3D have shown the electron flow in the diode to be unstable. Since this instability can potentially produce a non-uniform current and energy distribution in the hibachi structure and lasing medium it can be detrimental to laser efficiency. These results are similar to simulations performed using the ISIS code.(M.E. Jones and V.A. Thomas, Proceedings of the 8^th) International Conference on High-Power Particle Beams, 665 (1990). We have identified the instability as the so called ``transit-time" instability(C.K. Birdsall and W.B. Bridges, Electrodynamics of Diode Regions), (Academic Press, New York, 1966).^,(T.M. Antonsen, W.H. Miner, E. Ott, and A.T. Drobot, Phys. Fluids 27), 1257 (1984). and have investigated the role of the applied magnetic field and diode geometry. Experiments are underway to characterize the instability on the Nike KrF laser system and will be compared to simulation. Also some possible ways to mitigate the instability will be presented.

  7. Method and system for homogenizing diode laser pump arrays

    Science.gov (United States)

    Bayramian, Andy J

    2013-10-01

    An optical amplifier system includes a diode pump array including a plurality of semiconductor diode laser bars disposed in an array configuration and characterized by a periodic distance between adjacent semiconductor diode laser bars. The periodic distance is measured in a first direction perpendicular to each of the plurality of semiconductor diode laser bars. The diode pump array provides a pump output propagating along an optical path and characterized by a first intensity profile measured as a function of the first direction and having a variation greater than 10%. The optical amplifier system also includes a diffractive optic disposed along the optical path. The diffractive optic includes a photo-thermo-refractive glass member. The optical amplifier system further includes an amplifier slab having an input face and position along the optical path and separated from the diffractive optic by a predetermined distance. A second intensity profile measured at the input face of the amplifier slab as a function of the first direction has a variation less than 10%.

  8. Violet Laser Diode Enables Lighting Communication.

    Science.gov (United States)

    Chi, Yu-Chieh; Huang, Yu-Fang; Wu, Tsai-Chen; Tsai, Cheng-Ting; Chen, Li-Yin; Kuo, Hao-Chung; Lin, Gong-Ru

    2017-09-05

    Violet laser diode (VLD) based white-light source with high color rendering index (CRI) for lighting communication is implemented by covering with Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce) or Lu 3 Al 5 O 12 :Ce 3+ /CaAlSiN 3 :Eu 2+ (LuAG:Ce/CASN:Eu) phosphorous diffuser plates. After passing the beam of VLD biased at 70 mA (~2I th ) through the YAG:Ce phosphorous diffuser, a daylight with a correlated color temperature (CCT) of 5068 K and a CRI of 65 is acquired to provide a forward error correction (FEC) certified data rate of 4.4 Gbit/s. By using the VLD biased at 122 mA (~3.5I th ) to excite the LuAG:Ce/CASN:Eu phosphorous diffuser with 0.85-mm thickness, a warm white-light source with a CCT of 2700 K and a CRI of 87.9 is obtained at a cost of decreasing transmission capacity to 2.4 Gbit/s. Thinning the phosphor thickness to 0.75 mm effectively reduces the required bias current by 32 mA to achieve the same CCT for the delivered white light, which offers an enlarged CRI of 89.1 and an increased data rate of 4.4 Gbit/s. Further enlarging the bias current to 105 mA remains the white-light transmission capacity at 4.4 Gbit/s but reveals an increased CCT of 3023 K and an upgraded CRI of 91.5.

  9. GaN-based blue laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Miyajima, Takao; Yanashima, Katsunori; Funato, Kenji; Asatsuma, Tsunenori; Kobayashi, Toshimasa [CT Development Centre, CNC, Sony Corporation, Atsugi, Kanagawa (Japan); Tojyo, Tsuyoshi; Asano, Takeharu; Kijima, Satoru; Hino, Tomonori; Takeya, Motonobu; Uchida, Shiro; Ikeda, Masao [Sony Shiroishi Semiconductor Inc., Shiroishi, Miyagi (Japan); Tomiya, Shigetaka [Environment and Analyhsis Technology Department, Sony Corporation, Hodogaya, Yokohama (Japan)

    2001-08-13

    We report our recent progress on GaN-based high-power laser diodes (LDs), which will be applied as a light source in high-density optical storage systems. We have developed raised-pressure metal-organic chemical vapour deposition (RP-MOCVD), which can reduce the threading-dislocation density in the GaN layer to several times 10{sup 8} cm{sup -2}, and demonstrated continuous-wave (cw) operation of GaN-based LD grown by RP-MOCVD. Furthermore, we found that the epitaxial lateral overgrowth (ELO) technique is useful for further reducing threading-dislocation density to 10{sup 6} cm{sup -2} and reducing the roughness of the cleaved facet. By using this growth technique and optimizing device parameters, the lifetime of LDs was improved to more than 1000 hours under 30 mW cw operation at 60 deg. C. Our results proved that reducing both threading-dislocation density and consumption power is a valid approach to realizing a practical GaN-based LD. On the other hand, the practical GaN-based LD was obtained when threading-dislocation density in ELO-GaN was only reduced to 10{sup 6} cm{sup -2}, which is a relatively small reduction as compared with threading-dislocation density in GaAs- and InP-based LDs. We believe that the multiplication of non-radiative centres is very slow in GaN-based LDs, possibly due to the innate character of the GaN-based semiconductor itself. (author)

  10. Transscleral Diode Laser Cyclophotocoagulation in Refractory Glaucoma

    Directory of Open Access Journals (Sweden)

    Gülfidan Bitirgen

    2012-12-01

    Full Text Available Pur po se: To evaluate the safety and efficacy of transscleral diode laser cyclophotocoagulation (TSDLC in advanced glaucoma refractory to medical or surgical treatment. Ma te ri al and Met hod: The data of subjects who were treated with TSDLC between 2009 and 2011 were retrospectively reviewed. Intraocular pressure before and after treatment, visual acuity, the number of medications and complications were analysed. Success was defined as final IOP of 6-22 mmHg with or without antiglaucomatous medications. Re sults: Thirty seven eyes of 37 patients were included in the study. Mean age of patients and mean follow-up time were 61.73±17.13 years (range: 19-80 years and 8.06±5.81 months (range: 3-22 months, respectively. Mean pretreatment IOP was 38.68±8.94 mmHg and IOP was 26.46±11.34 mmHg (p <0.01 at the second week, whereas it was 24.97±10.84 mmHg (p<0.01 at the last visit. IOP of less than 22 mmHg was achieved in 40.5% of eyes at the last visit. Mean treatment number per eye was 1.48±0.73, and more than one treatment was required in 13 (35.1% eyes. Preoperative and postoperative mean total antiglaucomatous medications were 3.14±1.18 and 2.76±1.23, respectively. No phthisis bulbi or persistent hypotonia developed during the follow-up period. Dis cus si on: TSDLC is an effective and safe method for the treatment of refractory glaucoma. It also served to reduce the number of antiglaucoma medications, thus improving both the quality of life of the patients and their compliance to therapy. (Turk J Ophthalmol 2012; 42: 434-7

  11. Nanoengineering of organic light-emitting diodes

    International Nuclear Information System (INIS)

    Lupton, J.M.

    2000-11-01

    This thesis reports nanoengineerging of the emission and transport properties of organic light-emitting diodes (LEDs). This is achieved by a control of the electronic material properties and the photonic device properties. A novel class of conjugated materials for electroluminescence (EL) applications is presented, based on successively branching, or dendritic, materials comprising an emissive core and a shielding dendritic architecture. Exciton localisation at the centre of these dendrimers is observed in both luminescence and absorption. A detailed quantum chemical investigation using an exciton model supports these findings and accurately describes the energies and oscillator strengths of transitions in the core and branches. The dendrimer generation describes the degree of branching and gives a direct measure of the separation and interaction between chromophores. Increasing generation is found to lead to a reduction in red tail emission. This correlates with an increase in operating field and LED efficiency. Dendrimer blends with triplet harvesting dendritic phosphors are also investigated and found to exhibit unique emission properties. A numerical device model is presented, which is used to describe the temperature dependence of single layer polymer LEDs by fitting the field-dependent mobility and the barrier to hole injection. The device model is also used to obtain mobility values for the dendrimer materials, which are in excellent agreement with results obtained from time-of-flight measurements. The dendrimer generation is shown to provide a direct control of hopping mobility, which decreases by two orders of magnitude as the dendrimer generation increases from 0 to 3. The photonic properties and spontaneous emission of an LED are modified by incorporating a periodic wavelength scale microstructure into the emitting film. This is found to double the amount of light emitted with no effect on the device current. An investigation of the angular dependence

  12. Infrared diode laser spectroscopy of lithium hydride

    International Nuclear Information System (INIS)

    Yamada, C.; Hirota, E.

    1988-01-01

    The fundamental and hot bands of the vibration--rotation transitions of 6 LiH, 7 LiH, 6 LiD, and 7 LiD were observed by infrared diode laser spectroscopy at Doppler-limited resolution. Lithium hydride molecules were produced by the reaction of the Li vapor with hydrogen at elevated temperatures. Some 40 transitions were observed and, after combined with submillimeter-wave spectra reported by G. M. Plummer et al. [J. Chem. Phys. 81, 4893 (1984)], were analyzed to yield Dunham-type constants with accuracies more than an order of magnitude higher than those published in the literature. It was clearly demonstrated that the Born--Oppenheimer approximation did not hold, and some parameters representing the breakdown were evaluated. The Born--Oppenheimer internuclear distance r/sup BO//sub e/ was derived to be 1.594 914 26 (59) A, where a new value of Planck's constant recommended by CODATA was employed. The relative intensity of absorption lines was measured to determine the ratio of the permanent dipole moment to its first derivative with respect to the internuclear distance: μ/sub e/ [(partialμpartialr)/sub e/ r/sub e/ ] = 1.743(86). The pressure broadening parameter Δν/sub p/ P was determined to be 6.40 (22) MHzTorr by measuring the linewidth dependence on the pressure of hydrogen, which was about four times larger than the value for the dipole--quadrupole interaction estimated by Kiefer and Bushkovitch's theory

  13. Constant-current regulator improves tunnel diode threshold-detector performance

    Science.gov (United States)

    Cancro, C. A.

    1965-01-01

    Grounded-base transistor is placed in a tunnel diode threshold detector circuit, and a bias voltage is applied to the tunnel diode. This provides the threshold detector with maximum voltage output and overload protection.

  14. Proposal for the study of laminar relativistic electron beam generation by a foilless diode

    International Nuclear Information System (INIS)

    Jones, M.E.; Thode, L.E.

    1979-02-01

    The continuation of an analytical and numerical study of intense relativistic electron beam generation by foilless diodes is proposed. The investigation is aimed at optimizing the diode design to produce a laminar flow

  15. Determination of QW laser diode degradation based on the emission spectrum

    Directory of Open Access Journals (Sweden)

    Bliznyuk Vladimir

    2017-01-01

    Full Text Available The possibility of laser diodes degradation control by monitoring of their spectrum is shown. For red and infra-red laser diodes, the time dependence of the radiation spectrum width was obtained.

  16. Portable Diode Laser Diagnostic System for Collaborative Research on Air-Breathing Combustion

    National Research Council Canada - National Science Library

    Hanson, Ronald

    2003-01-01

    This equipment grant focused on four areas: (1) portable diode laser sensors with new fiber-coupled diode lasers and the support equipment to provide higher power with extended wavelength tuning range and speed; (2...

  17. Clinical experience with routine diode dosimetry for electron beam radiotherapy

    International Nuclear Information System (INIS)

    Yaparpalvi, Ravindra; Fontenla, Doracy P.; Vikram, Bhadrasain

    2000-01-01

    Purpose: Electron beam radiotherapy is frequently administered based on clinical setups without formal treatment planning. We felt, therefore, that it was important to monitor electron beam treatments by in vivo dosimetry to prevent errors in treatment delivery. In this study, we present our clinical experience with patient dose verification using electron diodes and quantitatively assess the dose perturbations caused by the diodes during electron beam radiotherapy. Methods and Materials: A commercial diode dosimeter was used for the in vivo dose measurements. During patient dosimetry, the patients were set up as usual by the therapists. Before treatment, a diode was placed on the patient's skin surface and secured with hypoallergenic tape. The patient was then treated and the diode response registered and stored in the patient radiotherapy system database via our in-house software. A customized patient in vivo dosimetry report showing patient details, expected and measured dose, and percent difference was then generated and printed for analysis and record keeping. We studied the perturbation of electron beams by diodes using film dosimetry. Beam profiles at the 90% prescription isodose depths were obtained with and without the diode on the beam central axis, for 6-20 MeV electron beams and applicator/insert sizes ranging from a 3-cm diameter circular field to a 25 x 25 cm open field. Results: In vivo dose measurements on 360 patients resulted in the following ranges of deviations from the expected dose at the various anatomic sites: Breast (222 patients) -20.3 to +23.5% (median deviation 0%); Head and Neck (63 patients) -21.5 to +14.8% (median -0.7%); Other sites (75 patients) -17.6 to +18.8% (median +0.5%). Routine diode dosimetry during the first treatment on 360 patients (460 treatment sites) resulted in 11.5% of the measurements outside our acceptable ±6% dose deviation window. Only 3.7% of the total measurements were outside ±10% dose deviation. Detailed

  18. Enhancement in performance of polycarbazole-graphene nanocomposite Schottky diode

    International Nuclear Information System (INIS)

    Pandey, Rajiv K.; Singh, Arun Kumar; Prakash, Rajiv

    2013-01-01

    We report formation of polycarbazole (PCz)–graphene nanocomposite over indium tin oxide (ITO) coated glass substrate using electrochemical technique for fabrication of high performance Schottky diodes. The synthesized nanocomposite is characterized before fabrication of devices for confirmation of uniform distribution of graphene nanosheets in the polymer matrix. Pure PCz and PCz-graphene nanocomposites based Schottky diodes are fabricated of configuration Al/PCz/ITO and Al/PCz-graphene nanocomposite/ITO, respectively. The current density–voltage (J-V) characteristics and diode performance parameters (such as the ideality factor, barrier height, and reverse saturation current density) are compared under ambient condition. Al/PCz-graphene nanocomposite/ITO device exhibits better ideality factor in comparison to the device formed using pure PCz. It is also observed that the Al/PCz-graphene nanocomposite/ITO device shows large forward current density and low turn on voltage in comparison to Al/PCz/ITO device

  19. Advancements of ultra-high peak power laser diode arrays

    Science.gov (United States)

    Crawford, D.; Thiagarajan, P.; Goings, J.; Caliva, B.; Smith, S.; Walker, R.

    2018-02-01

    Enhancements of laser diode epitaxy in conjunction with process and packaging improvements have led to the availability of 1cm bars capable of over 500W peak power at near-infrared wavelengths (770nm to 1100nm). Advances in cooler design allow for multi-bar stacks with bar-to-bar pitches as low as 350μm and a scalable package architecture enabled a single diode assembly with total peak powers of over 1MegaWatt of peak power. With the addition of micro-optics, overall array brightness greater than 10kW/cm2 was achieved. Performance metrics of barbased diode lasers specifically engineered for high peak power and high brightness at wavelengths and pulse conditions commonly used to pump a variety of fiber and solid-state materials are presented.

  20. Gate Modulation of Graphene-ZnO Nanowire Schottky Diode.

    Science.gov (United States)

    Liu, Ren; You, Xu-Chen; Fu, Xue-Wen; Lin, Fang; Meng, Jie; Yu, Da-Peng; Liao, Zhi-Min

    2015-05-06

    Graphene-semiconductor interface is important for the applications in electronic and optoelectronic devices. Here we report the modulation of the electric transport properties of graphene/ZnO nanowire Schottky diode by gate voltage (Vg). The ideality factor of the graphene/ZnO nanowire Schottky diode is ~1.7, and the Schottky barrier height is ~0.28 eV without external Vg. The Schottky barrier height is sensitive to Vg due to the variation of Fermi level of graphene. The barrier height increases quickly with sweeping Vg towards the negative value, while decreases slowly towards the positive Vg. Our results are helpful to understand the fundamental mechanism of the electric transport in graphene-semiconductor Schottky diode.

  1. Simulative research on reverse current in magnetically insulated coaxial diode

    Directory of Open Access Journals (Sweden)

    Danni Zhu

    2017-10-01

    Full Text Available The reverse current tends to occur in the transition region of the guiding magnetic field in a magnetically insulated coaxial diode (MICD. Influence of the guiding magnetic field on characteristics of the MICD especially on the reverse current is studied by the particle-in-cell (PIC simulation in this paper. The reverse current is confirmed to be irrelevant with the guiding magnetic field strength. However, the reverse current is clarified quantitatively to depend on the electric and magnetic field distribution in the upstream of the cathode tip. As the MICD has been widely employed in microwave tubes, a simple approach to suppress the reverse current on the premise of little change of the original diode is valuable and thus proposed. The optimum matching point between the cathode and the magnetic field is selected in consideration of the entrance depth tolerance, the diode impedance discrepancy and the reverse current coefficient.

  2. Maximum time-dependent space-charge limited diode currents

    Energy Technology Data Exchange (ETDEWEB)

    Griswold, M. E. [Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States); Fisch, N. J. [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)

    2016-01-15

    Recent papers claim that a one dimensional (1D) diode with a time-varying voltage drop can transmit current densities that exceed the Child-Langmuir (CL) limit on average, apparently contradicting a previous conjecture that there is a hard limit on the average current density across any 1D diode, as t → ∞, that is equal to the CL limit. However, these claims rest on a different definition of the CL limit, namely, a comparison between the time-averaged diode current and the adiabatic average of the expression for the stationary CL limit. If the current were considered as a function of the maximum applied voltage, rather than the average applied voltage, then the original conjecture would not have been refuted.

  3. Planar transistors and impatt diodes with ion implantation

    International Nuclear Information System (INIS)

    Dorendorf, H.; Glawischnig, H.; Grasser, L.; Hammerschmitt, J.

    1975-03-01

    Low frequency planar npn and pnp transistors have been developed in which the base and emitter have been fabricated using ion implantation of boron and phosphorus by a drive-in diffusion. Electrical parameters of the transistors are comparable with conventionally produced transistors; the noise figure was improved and production tolerances were significantly reduced. Silicon-impatt diodes for the microwave range were also fabricated with implanted pn junctions and tested for their high frequency characteristics. These diodes, made in an improved upside down technology, delivered output power up to 40 mW (burn out power) at 30 GHz. Reverse leakage current and current carrying capability of these diodes were comparable to diffused structures. (orig.) 891 ORU 892 MB [de

  4. Origin of Negative Capacitance in Bipolar Organic Diodes

    Science.gov (United States)

    Niu, Quan; Crǎciun, N. Irina; Wetzelaer, Gert-Jan A. H.; Blom, Paul W. M.

    2018-03-01

    Negative differential capacitance (NC) occurring at low frequencies in organic light-emitting diodes (OLEDs) is a poorly understood phenomenon. We study the origin of the NC effect by systematically varying the number of electron traps in OLEDs based on the polymeric semiconductor poly(p -phenylene vinylene). Increasing the electron trap density enhances the NC effect. The magnitude and observed decrease of the relaxation time is consistent with the (inverse) rate of trap-assisted recombination. The absence of NC in a nearly trap-free light-emitting diode unambiguously shows that trap-assisted recombination is the responsible mechanism for the negative contribution to the capacitance in bipolar organic diodes. Our results reveal that the NC effect can be exploited to quantitatively determine the number of traps in organic semiconductors in a nondestructive fashion.

  5. To the problem of electron beam production in plasma diodes

    International Nuclear Information System (INIS)

    Korenev, S.A.

    1982-01-01

    The results of exprriments on electrOn beam generation from plasma emitting surfaces formed by incompleted charged over the dielectric surface, sliding charge over the dielectric surface covered with a layer of barium oxide, discharge due to explosion-emission effects. The experiments have shown that the formed plasma of sliding discharge and discharge in explosion-emission effects is rather homogeneous and the electron beam has the current density homogeneity in the transverse cross section of approximation 20%. At the diode voltage of 150-300 kV the density of electron current for diodes with cathode on the basis of the sliding charge is approximately 0.4-1.0 kA/cm 2 , while for diodes with cathode made of graphite with metallic grid it is approximately 0.5-1.3 kA/cm 2 . The average gap between anode and cathode is 1 cm for both cases

  6. Blue laser diode (450 nm) systems for welding copper

    Science.gov (United States)

    Silva Sa, M.; Finuf, M.; Fritz, R.; Tucker, J.; Pelaprat, J.-M.; Zediker, M. S.

    2018-02-01

    This paper will discuss the development of high power blue laser systems for industrial applications. The key development enabling high power blue laser systems is the emergence of high power, high brightness laser diodes at 450 nm. These devices have a high individual brightness rivaling their IR counterparts and they have the potential to exceed their performance and price barriers. They also have a very high To resulting in a 0.04 nm/°C wavelength shift. They have a very stable lateral far-field profile which can be combined with other diodes to achieve a superior brightness. This paper will report on the characteristics of the blue laser diodes, their integration into a modular laser system suitable for scaling the output power to the 1 kW level and beyond. Test results will be presented for welding of copper with power levels ranging from 150 Watts to 600 Watts

  7. High-brightness tapered laser diodes with photonic crystal structures

    Science.gov (United States)

    Li, Yi; Du, Weichuan; Kun, Zhou; Gao, Songxin; Ma, Yi; Tang, Chun

    2018-02-01

    Beam quality of tapered laser diodes is limited by higher order lateral mode. On purpose of optimizing the brightness of tapered laser diodes, we developed a novel design of tapered diodes. This devices based on InGaAs/AlGaAs asymmetry epitaxial structure, containing higher order lateral mode filtering schemes especially photonic crystal structures, which fabricated cost effectively by using standard photolithography and dry etch processes. Meanwhile, the effects of photonic crystal structures on mode control are also investigated theoretically by FDBPM (Finite-Difference Beam Propagation Method) calculation. We achieved a CW optical output power of 6.9W at 940nm for a single emitter with 4 mm cavity length. A nearly diffraction limited beam of M2 ≍1.9 @ 0.5W has been demonstrated, and a highest brightness of β =75MW/(cm2 ·sr) was reached.

  8. High Power Diode Lasers with External Feedback: Overview and Prospects

    DEFF Research Database (Denmark)

    Chi, Mingjun; Petersen, Paul Michael

    2012-01-01

    In summary, different external-cavity feedback techniques to improve the spatial beam quality and narrow the linewidth of the output beam from both BALs and TDLs are presented. Broad-area diode laser system with external-cavity feedback around 800 nm can produce several Watts of output power...... with a good beam quality. Tapered diode laser systems with external-cavity feedback around 800 and 1060 nm can deliver more than 2 W output power with diffraction-limited beam quality and can be operated in single-longitudinal mode. These high-brightness, narrow linewidth, and tunable external-cavity diode...... lasers emerge as the next generation of compact lasers that have the potential of replacing conventional high power laser systems in many existing applications....

  9. Resonance ionization mass spectrometry using tunable diode lasers

    International Nuclear Information System (INIS)

    Shaw, R.W.; Young, J.P.; Smith, D.H.

    1990-01-01

    Tunable semiconductor diode lasers will find many important applications in atomic spectroscopy. They exhibit the desirable attributes of lasers: narrow bandwidth, tunability, and spatial coherence. At the same time, they possess few of the disadvantages of other tunable lasers. They require no alignment, are simple to operate, and are inexpensive. Practical laser spectroscopic instruments can be envisioned. The authors have applied diode lasers to resonance ionization mass spectrometry (RIMS) of some of the lanthanide elements. Sub-Doppler resolution spectra have been recorded and have been used for atomic hyperfine structure analysis. Isotopically-selective ionization has been accomplished, even in cases where photons from a broadband dye laser are part of the overall ionization process and where the isotopic spectral shift is very small. A convenient RIMS instrument for isotope ratio measurements that employs only diode lasers, along with electric field ionization, should be possible

  10. Dose rate and SDD dependence of commercially available diode detectors

    International Nuclear Information System (INIS)

    Saini, Amarjit S.; Zhu, Timothy C.

    2004-01-01

    The dose-rate dependence of commercially available diode detectors was measured under both high instantaneous dose-rate (pulsed) and low dose rate (continuous, Co-60) radiation. The dose-rate dependence was measured in an acrylic miniphantom at a 5-cm depth in a 10x10 cm 2 collimator setting, by varying source-to-detector distance (SDD) between at least 80 and 200 cm. The ratio of a normalized diode reading to a normalized ion chamber reading (both at SDD=100 cm) was used to determine diode sensitivity ratio for pulsed and continuous radiation at different SDD. The inverse of the diode sensitivity ratio is defined as the SDD correction factor (SDD CF). The diode sensitivity ratio increased with increasing instantaneous dose rate (or decreasing SDD). The ratio of diode sensitivity, normalized to 4000 cGy/s, varied between 0.988 (1490 cGy/s)-1.023 (38 900 cGy/s) for unirradiated n-type Isorad Gold, 0.981 (1460 cGy/s)-1.026 (39 060 cGy/s) for unirradiated QED Red (n type), 0.972 (1490 cGy/s)-1.068 (38 900 cGy/s) for preirradiated Isorad Red (n type), 0.985 (1490 cGy/s)-1.012 (38 990 cGy/s) for n-type Pt-doped Isorad-3 Gold, 0.995 (1450 cGy/s)-1.020 (21 870 cGy/s) for n-type Veridose Green, 0.978 (1450 cGy/s)-1.066 (21 870 cGy/s) for preirradiated Isorad-p Red, 0.994 (1540 cGy/s)-1.028 (17 870 cGy/s) for p-type preirradiated QED, 0.998 (1450 cGy/s)-1.003 (21 870 cGy/s) for the p-type preirradiated Scanditronix EDP20 3G , and 0.998 (1490 cGy/s)-1.015 (38 880 cGy/s) for Scanditronix EDP10 3G diodes. The p-type diodes do not always show less dose-rate dependence than the n-type diodes. Preirradiation does not always reduce diode dose-rate dependence. A comparison between the SDD dependence measured at the surface of a full scatter phantom and that in a miniphantom was made. Using a direct adjustment of radiation pulse height, we concluded that the SDD dependence of diode sensitivity can be explained by the instantaneous dose-rate dependence if sufficient buildup is

  11. Examinations of Selected Thermal Properties of Packages of SiC Schottky Diodes

    Directory of Open Access Journals (Sweden)

    Bisewski Damian

    2016-09-01

    Full Text Available This paper describes the study of thermal properties of packages of silicon carbide Schottky diodes. In the paper the packaging process of Schottky diodes, the measuring method of thermal parameters, as well as the results of measurements are presented. The measured waveforms of transient thermal impedance of the examined diodes are compared with the waveforms of this parameter measured for commercially available Schottky diodes.

  12. Experimental evidence of energetic neutrals production in an ion diode

    Energy Technology Data Exchange (ETDEWEB)

    Pushkarev, A.I., E-mail: aipush@mail.ru; Isakova, Y.I.; Khaylov, I.P.

    2015-01-15

    The paper presents several experimental proofs of the formation of energetic charge-exchange neutrals in a self-magnetically insulated ion diode with a graphite cathode. The energetic neutrals are thought to be produced as a result of charge exchange process between accelerated ions and stationary neutral molecules. The experiments have been carried out using both a diode with externally applied magnetic insulation (single-pulse mode: 100 ns, 250–300 kV) and a diode with self-magnetic insulation (double-pulse mode: 300–500 ns, 100–150 kV (negative pulse); 120 ns, 250–300 kV (positive pulse)). The motivation for looking at the neutral component of the ion beam came when we compared two independent methods to measure the energy density of the beam. A quantitative comparison of infrared measurements with signals from Faraday cups and diode voltage was made to assess the presence of neutral atoms in the ion beam. As another proof of charge-exchange effects in ion diode we present the results of statistical analysis of diode performance. It was found that the shot-to shot variation of the energy density in a set of 50–100 shots does not exceed 11%, whilst the same variation for ion current density was 20–30%; suggesting the presence of neutrals in the beam. Moreover, the pressure in the zone of ion beam energy dissipation exceeds the results stated in cited references. The difference between our experimental data and results stated by other authors we attribute to the presence of a low-energy charge-exchange neutral component in the ion beam.

  13. Subpicosecond gain dynamics in GaAlAs laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kesler, M.P.; Ippen, E.P.

    1987-11-30

    Ultrafast gain dynamics in GaAlAs diode amplifiers have been studied using 100 fs optical pulses. Pulse propagation through the amplifier resulted in temporal broadening and pulse shaping due to both gain saturation and material dispersion. Pump-probe experiments indicate the presence of two processes contributing to the gain dynamics but give no evidence of spectral hole burning. A dynamic carrier heating model is presented to explain all of the observed gain nonlinearities, and the implications of our results on the dynamic response of laser diodes are discussed.

  14. Gate Modulation of Graphene-ZnO Nanowire Schottky Diode

    OpenAIRE

    Liu, Ren; You, Xu-Chen; Fu, Xue-Wen; Lin, Fang; Meng, Jie; Yu, Da-Peng; Liao, Zhi-Min

    2015-01-01

    Graphene-semiconductor interface is important for the applications in electronic and optoelectronic devices. Here we report the modulation of the electric transport properties of graphene/ZnO nanowire Schottky diode by gate voltage (Vg). The ideality factor of the graphene/ZnO nanowire Schottky diode is ~1.7, and the Schottky barrier height is ~0.28?eV without external Vg. The Schottky barrier height is sensitive to Vg due to the variation of Fermi level of graphene. The barrier height increa...

  15. Electrically driven surface plasmon light-emitting diodes

    DEFF Research Database (Denmark)

    Fadil, Ahmed; Ou, Yiyu; Iida, Daisuke

    We investigate device performance of GaN light-emitting diodes (LEDs) with a 30-nm p-GaN layer. The metallization used to separate the p-contact from plasmonic metals, reveals limitations on current spreading which reduces surface plasmonic enhancement.......We investigate device performance of GaN light-emitting diodes (LEDs) with a 30-nm p-GaN layer. The metallization used to separate the p-contact from plasmonic metals, reveals limitations on current spreading which reduces surface plasmonic enhancement....

  16. 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.

  17. Generation conditions of CW Diode Laser Sustained Plasma

    Science.gov (United States)

    Nishimoto, Koji; Matsui, Makoto; Ono, Takahiro

    2016-09-01

    Laser sustained plasma was generated using 1 kW class continuous wave diode laser. The laser beam was focused on the seed plasma generated by arc discharge in 1 MPa xenon lamp. The diode laser has advantages of high energy conversion efficiency of 80%, ease of maintenance, compact size and availability of conventional quartz based optics. Therefore, it has a prospect of further development compared with conventional CO2 laser. In this study, variation of the plasma shape caused by laser power is observed and also temperature distribution in the direction of plasma radius is measured by optical emission spectroscopy.

  18. 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.

    2018-01-02

    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.

  19. Computer-assisted experiments with a laser diode

    Energy Technology Data Exchange (ETDEWEB)

    Kraftmakher, Yaakov, E-mail: krafty@mail.biu.ac.il [Department of Physics, Bar-Ilan University, Ramat-Gan 52900 (Israel)

    2011-05-15

    A laser diode from an inexpensive laser pen (laser pointer) is used in simple experiments. The radiant output power and efficiency of the laser are measured, and polarization of the light beam is shown. The h/e ratio is available from the threshold of spontaneous emission. The lasing threshold is found using several methods. With a data-acquisition system, the measurements are possible in a short time. The frequency response of the laser diode is determined in the range 10-10{sup 7} Hz. The experiments are suitable for undergraduate laboratories and for classroom demonstrations on semiconductors.

  20. Computer-assisted experiments with a laser diode

    International Nuclear Information System (INIS)

    Kraftmakher, Yaakov

    2011-01-01

    A laser diode from an inexpensive laser pen (laser pointer) is used in simple experiments. The radiant output power and efficiency of the laser are measured, and polarization of the light beam is shown. The h/e ratio is available from the threshold of spontaneous emission. The lasing threshold is found using several methods. With a data-acquisition system, the measurements are possible in a short time. The frequency response of the laser diode is determined in the range 10-10 7 Hz. The experiments are suitable for undergraduate laboratories and for classroom demonstrations on semiconductors.

  1. System and method for high power diode based additive manufacturing

    Science.gov (United States)

    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.

  2. Daily check of the electron beams with a diode system

    Energy Technology Data Exchange (ETDEWEB)

    Pilette, P [Hospital Civil de Charleroi (Belgium). Centre for Radiotherapy

    1995-12-01

    A fast systems to check all the accelerator beams on a daily basis has been developed. A cheap home-made detector, based on non-medical diodes (type 1N5408), has been used since July 1992 to verify all the electron beams every day. The relative energy and Top-cGy correspondence is verified with one single irradiation of less than 1 minute by 6 diodes fixed in a polystyrene phantom. The principle of construction, software implementation and results are presented.

  3. Mathematical modeling of a passively Q-switched diode laser

    International Nuclear Information System (INIS)

    Abdul Ghani, B.; Hammadi, M.

    2009-11-01

    A mathematical model describing the dynamic emission of the intracavity frequency doubling (IFD) of a gain-switched InGaAs/GaAs/KTP and a gain-switched mode-locked two-sections tapered ridge-waveguide InGaAs/GaAs diode laser has been presented. The IFD of a gain-switched and a gain-switched mode-locked two-sections diode laser is modeled where one section is electrically pumped to proved gain while the second section is unpumped (reverse biased) to provide a saturable absorber. (author)

  4. Study on the plasma diode in the external magnetic field

    International Nuclear Information System (INIS)

    Korenev, S.A.

    1981-01-01

    The experimental investigations of plasma diode with cathode plasma formation on the basis of an incomplete charge over dielectric surface in the external longitudinal magnetic field with the intensity of Hsub(z) up to 2000 Oe are presented. It is demonstrated that at the 150-250 keV diode voltage and the current density of up to 300 A/cm 2 the homogeneity of the current density over transverse cross section is preserved up to the cell size of metallic grid onto cathode with the change of the magnetic field up to 2000 Oe [ru

  5. Diode-pumped solid state laser for inertial fusion energy

    International Nuclear Information System (INIS)

    Payne, S.A.; Krupke, W.F.; Orth, C.D.

    1994-11-01

    The authors evaluate the prospect for development of a diode-pumped solid-state-laser driver in an inertial fusion energy power plant. Using a computer code, they predict that their 1 GWe design will offer electricity at 8.6 cents/kW · hr with the laser operating at 8.6% efficiency and the recycled power level at 31%. The results of their initial subscale experimental testbed of a diode-pumped solid state laser are encouraging, demonstrating good efficiencies and robustness

  6. Velocity spread of REB generated by high current diode

    International Nuclear Information System (INIS)

    Vrba, P.

    1994-05-01

    A theoretical analysis and numerical simulations of the Relativistic Electron Beam (REB) generation in a high current diode immersed in an external magnetic field were performed. The calculations confirmed the generated beam to be homogeneous and monoenergetic in a broad central region. In the case of a cylindrical diode the mixing of electron trajectories was only observed in a narrow peripheral beam region. The angle between particle trajectories and the external longitudinal magnetic field varies chaotically form 0 to -25 deg. This phenomenon suppresses the excitation of the two-stream instability excited by REB in a plasma column. (author) 2 tabs., 12 figs., 7 refs

  7. Characteristic of laser diode beam propagation through a collimating lens.

    Science.gov (United States)

    Xu, Qiang; Han, Yiping; Cui, Zhiwei

    2010-01-20

    A mathematical model of a laser diode beam propagating through a collimating lens is presented. Wave propagation beyond the paraxial approximation is studied. The phase delay of the laser diode wave in passing through the lens is analyzed in detail. The propagation optical field after the lens is obtained from the diffraction integral by the stationary phase method. The model is employed to predict the light intensity at various beam cross sections, and the computed intensity distributions are in a good agreement with the corresponding measurements.

  8. Thermal sensor based zinc oxide diode for low temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    Ocaya, R.O. [Department of Physics, University of the Free State (South Africa); Al-Ghamdi, Ahmed [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah, 21589 (Saudi Arabia); El-Tantawy, F. [Department of Physics, Faculty of Science, Suez Canal University, Ismailia (Egypt); Center of Nanotechnology, King Abdulaziz University, Jeddah (Saudi Arabia); Farooq, W.A. [Department of Physics and Astronomy, College of Science, King Saud University, Riyadh (Saudi Arabia); Yakuphanoglu, F., E-mail: fyhan@hotmail.com [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah, 21589 (Saudi Arabia); Department of Physics, Faculty of Science, Firat University, Elazig, 23169 (Turkey)

    2016-07-25

    The device parameters of Al/p-Si/Zn{sub 1-x}Al{sub x}O-NiO/Al Schottky diode for x = 0.005 were investigated over the 50 K–400 K temperature range using direct current–voltage (I–V) and impedance spectroscopy. The films were prepared using the sol–gel method followed by spin-coating on p-Si substrate. The ideality factor, barrier height, resistance and capacitance of the diode were found to depend on temperature. The calculated barrier height has a mean. Capacitance–voltage (C–V) measurements show that the capacitance decreases with increasing frequency, suggesting a continuous distribution of interface states over the surveyed 100 kHz to 1 MHz frequency range. The interface state densities, N{sub ss}, of the diode were calculated and found to peak as functions of bias and temperature in two temperature regions of 50 K–300 K and 300 K–400 K. A peak value of approximately 10{sup 12}/eV cm{sup 2} was observed around 0.7 V bias for 350 K and at 3 × 10{sup 12}/eVcm{sup 2} around 2.2 V bias for 300 K. The relaxation time was found to average 4.7 μs over all the temperatures, but showing its lowest value of 1.58 μs at 300 K. It is seen that the interface states of the diode is controlled by the temperature. This suggests that Al/p-Si/Zn1-xAlxO-NiO/Al diode can be used as a thermal sensors for low temperature applications. - Highlights: • Al/pSi/Zn1-xAlxO-NiO/Al Schottky diode was fabricated by sol gel method. • The interface state density of the diode is controlled by the temperature. • Zinc oxide based diode can be used as a thermal sensor for low temperature applications.

  9. Precision Spectroscopy, Diode Lasers, and Optical Frequency Measurement Technology

    Science.gov (United States)

    Hollberg, Leo (Editor); Fox, Richard (Editor); Waltman, Steve (Editor); Robinson, Hugh

    1998-01-01

    This compilation is a selected set of reprints from the Optical Frequency Measurement Group of the Time and Frequency Division of the National Institute of Standards and Technology, and consists of work published between 1987 and 1997. The two main programs represented here are (1) development of tunable diode-laser technology for scientific applications and precision measurements, and (2) research toward the goal of realizing optical-frequency measurements and synthesis. The papers are organized chronologically in five, somewhat arbitrarily chosen categories: Diode Laser Technology, Tunable Laser Systems, Laser Spectroscopy, Optical Synthesis and Extended Wavelength Coverage, and Multi-Photon Interactions and Optical Coherences.

  10. Distributed-feedback single heterojunction GaAs diode laser

    International Nuclear Information System (INIS)

    Scifres, D.R.; Burnham, R.D.; Streifer, W.

    1974-01-01

    Laser operation of single-heterojunction GaAl As/GaAs diode lasers using a periodic structure within the gain medium of the device, thereby obviating the need for carefully cleaved end crystal faces to produce feedback, is reported. By varying the grating period, wavelengths from 8430 to 8560 A were observed. The threshold current densities were of the same order as for normal single heterojunction diode lasers. Some advantages in output wavelengths were observed over lasers with cleared faces. (U.S.)

  11. Photoresponse of poly(para-phenylenevinylene) light-emitting diodes

    International Nuclear Information System (INIS)

    Wei, X.; Raikh, M.; Vardeny, Z.V.; Yang, Y.; Moses, D.

    1994-01-01

    We have studied the photoresponses of poly(para-phenylene vinylene) (PPV) light-emitting diodes (LED's) with PPV derivatives sandwiched between tin oxide (ITO) and metals including calcium, aluminum, and copper. Under illumination all diodes exhibit relatively large photoconductive I(V) responses which cross the dark I(V) curve at a forward-bias voltage V 0 that scales with the difference in work functions between the ITO and metal electrodes, the open-circuit voltage saturates at V 0 and is temperature independent, and the enhanced electroluminescence intensity of the illuminated LED's correlates with the photocurrent

  12. Degradation of light emitting diodes: a proposed methodology

    International Nuclear Information System (INIS)

    Koh, Sau; Vam Driel, Willem; Zhang, G.Q.

    2011-01-01

    Due to their long lifetime and high efficacy, light emitting diodes have the potential to revolutionize the illumination industry. However, self heat and high environmental temperature which will lead to increased junction temperature and degradation due to electrical overstress can shorten the life of the light emitting diode. In this research, a methodology to investigate the degradation of the LED emitter has been proposed. The epoxy lens of the emitter can be modelled using simplified Eyring methods whereas an equation has been proposed for describing the degradation of the LED emitters. (semiconductor devices)

  13. Direct-current polarization characteristics of various AlGaAs laser diodes

    Science.gov (United States)

    Fuhr, P. L.

    1984-01-01

    Polarization characteristics of AlGaAs laser diodes having various device geometries have been measured. Measurements were performed with the laser diodes operating under dc conditions. Results show that laser diodes having different device geometries have optical outputs that exhibit varying degrees of polarization purity. Implications of this result, with respect to incoherent polarization-beam combining, are addressed.

  14. A Novel Current-Mode Full-Wave Rectifier Based on One CDTA and Two Diodes

    Directory of Open Access Journals (Sweden)

    F. Khateb

    2010-09-01

    Full Text Available Precision rectifiers are important building blocks for analog signal processing. The traditional approach based on diodes and operational amplifiers (OpAmps exhibits undesirable effects caused by limited OpAmp slew rate and diode commutations. In the paper, a full-wave rectifier based on one CDTA and two Schottky diodes is presented. The PSpice simulation results are included.

  15. Recent developments in white light emitting diodes

    Science.gov (United States)

    Lohe, P. P.; Nandanwar, D. V.; Belsare, P. D.; Moharil, S. V.

    2018-05-01

    because they can emit visible light strongly under blue light irradiation. These are chemically, thermally and mechanically stable materials with high efficiency to down convert blue radiation into green and red. Efficient white light can be generated by coating these phosphors on blue LED.CRI of white emitting LED lamp can be improved significantly if green and red emitting phosphors are coated on efficient blue emitting LED chips. In this approach CRI will be maintained if appropriate combination of red, green along with blue emission is used. This article reviews some recent developments in phosphors for white light emitting diodes.

  16. Electron dosimetry in irradiation processing with rad-hard diodes

    International Nuclear Information System (INIS)

    Santos, Thais Cavalheri dos

    2012-01-01

    This work had the aim of the development of dosimetric systems based on Si special diodes, resistant to radiation damage to online monitoring of irradiation processing using 1.5 MeV electrons energy and for relative dosimetry and clinical electron beam scanning within an energy range of 6 MeV up to 21 MeV. The diodes used were produced by Float Zone standard (FZ), Magnetic Czochralski (MCz) and epitaxy growth (EPI) methods. In order to use the diodes as detectors, they were fixed on alumina base to allow the connection of the polarization electrodes and the signals extraction. After the diode assembly on the base, each one was housed in a black acrylic probe with aluminized Mylar® window and LEMO® connector. With the devices operating in photovoltaic mode, the integration of the current signals as a function of irradiation time allowed obtain the charge produced in the sensitive volume of each diode irradiated. The electron accelerator used for high doses irradiation was the DC 1500/25/4 JOB 188 of the 1.5 MeV installed at the Radiation Technology Center of the IPEN/CNEN-SP. The current profile as function of exposure time, the response repeatability, the sensitivity as function of absorbed dose and the dose response curve were studied for each device. In comparison to FZ diode, we observed a greater decrease in the sensitivity for MCz diode, and good repeatability in both cases. Also, the increasing of the charge with the absorbed dose was well fitted by a second order polynomial function. In the EPI diode characterization, this one exhibited repeatability better than CTA dosimeters applied routinely in radiation processing. The above results indicate the potential use of these radiation hardness Si diodes in online dosimetry to high doses applications. For low doses irradiation were used the linear accelerators KD2 and Primus, both manufactured by Siemens and located at Sirio-Libanes Hospital. The diodes responses were evaluated for electron beams within the

  17. Intense pulsed light-ion beam generated by planar type self-magnetically insulated diode

    International Nuclear Information System (INIS)

    Yoshikawa, T.; Masugata, K.; Ito, M.; Matsui, M.; Yatsui, K.

    1984-01-01

    New type of ion diode named ''Planar Type Self-Magnetically Insulated Diode'' (PSID) has been developed. By using a 1.5-mm-thick-polyethylene sheet as an anode surface, we have obtained Vsub(d) (diode voltage) -- 886 kV, Isub(d) (diode current) -- 180 kA, and Isub(i) (net ion current) -- 52 kA, yielding the diode efficiency of ion production to be -- 30 %. Multiple-shots operation (more than 40 shots) has been possible with good reproducibility in such a relatively high powers above. (author)

  18. Current in heavy-current planar diode with discrete emission surface

    International Nuclear Information System (INIS)

    Belomyttsev, S.Ya.; Korovin, S.D.; Pegel', I.V

    1999-01-01

    Dependence of current in a high-current planar diode on the size of emission centres was studied. Essential effect of emission surface microstructure on the current value in the planar diode was demonstrated. It was determined that if the distance between the emitter essentially exceeded their size then current dependence on the ratio of size to the value of the diode gap was an exponential function with 3/2 index. Current dependence on voltage obeyed the exponential law with 3/2 index up to higher voltage values in the planar diode with discrete emission surface in contrast to the case of a planar diode with homogeneous emission surface [ru

  19. Comparative study of Si diodes for gamma radiation dosimetry

    International Nuclear Information System (INIS)

    Pascoalino, Kelly Cristina da Silva

    2010-01-01

    In this work it is presented the comparative study of Si diodes response for gamma radiation dosimetry. The diodes investigated, grown by float zone (Fz) and magnetic Czochralski (MCz) techniques, were processed at the Physics Institute of Helsinki University in the framework of the research and development of rad-hard silicon devices. To study the dosimetric response of these diodes they were connected in the photovoltaic mode to the input of a digital electrometer to measure the photocurrent signal due to the incidence of gamma-rays from a 60 Co source (Gammacell 220). The dosimetric parameter utilized to study the response of these devices was the charge, obtained trough the integration of the current signals, as a function of the absorbed dose. Studies of the influence of the pre-irradiation procedures on both sensitivity and stability of these diodes showed that the sensitivity decreased with the total absorbed dose but after a preirradiation of about 873 kGy they became more stable. Radiation damage effects eventually produced in the devices were monitored trough dynamic current and capacitance measurements after each irradiation step. Both samples also exhibited good response reproducibility, 2,21% (Fz) and 2,94% (MCz), obtained with 13 consecutive measurements of 15 kGy compared with the equivalent 195 kGy absorbed dose in one step of irradiation. It is important to note that these results are better than those obtained with routine polymethylmethacrylate (PMMA) dosimeters used in radiation processing dosimetry. (author)

  20. Foil-less plasma-filled diode for HPM generator

    International Nuclear Information System (INIS)

    Eltchaninov, A A; Kovalchuk, B M; Kurkan, I K; Zherlitsyn, A A

    2014-01-01

    Plasma-filled diode regarded as perspective source of electron beam feeding HPM generator of GW power level, comparing to conventional explosive emission vacuum diode. Electron beam generation occurs in plasma double layer, where plasma boundary plays as an anode. It allows cancelling the usage of anode foils or grids in HPM generators with the virtual cathode, which could limit its life time to few shots. The presence of ions in the e-beam drift space could raise the limiting current for a drift space, but it could affect to microwave generation also. Sectioned plasma-filled diode with beam current of about 100 kA, electron beam energy of about 0.5 MV and beam current density of 1-10 kA/cm 2 was realized. Cylindrical transport channel with the diameter of 200 mm and the length of about 30 cm was attached to the diode. Beam current measurements in a drift space were performed. Computer simulations of electron beam transport with the presence of ions were carried out with the 2.5D axisymmetric version of PiC-code KARAT. Obtained results would help optimizing electrodynamic system of HPM generator subjected to the presence of ions

  1. Fabrication and characterization of the charge-plasma diode

    NARCIS (Netherlands)

    Rajasekharan, B.; Hueting, Raymond Josephus Engelbart; Salm, Cora; van Hemert, T.; Wolters, Robertus A.M.; Schmitz, Jurriaan

    2010-01-01

    We present a new lateral Schottky-based rectifier called the charge-plasma diode realized on ultrathin silicon-oninsulator. The device utilizes the workfunction difference between two metal contacts, palladium and erbium, and the silicon body. We demonstrate that the proposed device provides a low

  2. A Biological Porin Engineered into a Molecular, Nanofluidic Diode

    NARCIS (Netherlands)

    Miedema, Henk; Vrouenraets, Maarten; Wierenga, Jenny; Meijberg, Wim; Robillard, George; Eisenberg, Bob

    2007-01-01

    We changed the nonrectifying biological porin OmpF into a nanofluidic diode. To that end, we engineered a pore that possesses two spatially separated selectivity filters of opposite charge where either cations or anions accumulate. The observed current inhibition under applied reverse bias voltage

  3. In-volume heating using high-power laser diodes

    NARCIS (Netherlands)

    Denisenkov, V.S.; Kiyko, V.V.; Vdovin, G.V.

    2015-01-01

    High-power lasers are useful instruments suitable for applications in various fields; the most common industrial applications include cutting and welding. We propose a new application of high-power laser diodes as in-bulk heating source for food industry. Current heating processes use surface

  4. Diode-Assisted Buck-Boost Current Source Inverters

    DEFF Research Database (Denmark)

    Gao, F.; Cai, Liang; Loh, P.C.

    2007-01-01

    This paper presents a couple of novel current source inverters (CSIs) with the enhanced current buckboost capability. With the unique diode-inductor network added between current source inverter circuitry and current boost elements, the proposed buck-boost current source inverters demonstrate...... uninfluenced. Lastly, all theoretical findings were verified experimentally using constructed laboratory prototypes....

  5. Organic light emitting diodes with spin polarized electrodes

    NARCIS (Netherlands)

    Arisi, E.; Bergenti, I.; Dediu, V.; Loi, M.A.; Muccini, M.; Murgia, M.; Ruani, G.; Taliani, C.; Zamboni, R.

    2003-01-01

    Electrical and optical properties of Alq3 based organic light emitting diodes with normal and spin polarized electrodes are presented. Epitaxial semitransparent highly spin polarized La0.7Sr0.3MnO3 were used as hole injector, substituting the traditional indium tin oxide electrode. A comparison of

  6. Time series analysis in chaotic diode resonator circuit

    Energy Technology Data Exchange (ETDEWEB)

    Hanias, M.P. [TEI of Chalkis, GR 34400, Evia, Chalkis (Greece)] e-mail: mhanias@teihal.gr; Giannaris, G. [TEI of Chalkis, GR 34400, Evia, Chalkis (Greece); Spyridakis, A. [TEI of Chalkis, GR 34400, Evia, Chalkis (Greece); Rigas, A. [TEI of Chalkis, GR 34400, Evia, Chalkis (Greece)

    2006-01-01

    A diode resonator chaotic circuit is presented. Multisim is used to simulate the circuit and show the presence of chaos. Time series analysis performed by the method proposed by Grasberger and Procaccia. The correlation and minimum embedding dimension {nu} and m {sub min}, respectively, were calculated. Also the corresponding Kolmogorov entropy was calculated.

  7. Time series analysis in chaotic diode resonator circuit

    International Nuclear Information System (INIS)

    Hanias, M.P.; Giannaris, G.; Spyridakis, A.; Rigas, A.

    2006-01-01

    A diode resonator chaotic circuit is presented. Multisim is used to simulate the circuit and show the presence of chaos. Time series analysis performed by the method proposed by Grasberger and Procaccia. The correlation and minimum embedding dimension ν and m min , respectively, were calculated. Also the corresponding Kolmogorov entropy was calculated

  8. Liquid metals as electrodes in polymer light emitting diodes

    NARCIS (Netherlands)

    Andersson, G.G.; Gommans, H.H.P.; Denier van der Gon, A.W.; Brongersma, H.H.

    2003-01-01

    We demonstrate that liquid metals can be used as cathodes in light emitting diodes (pLEDs). The main difference between the use of liquid cathodes and evaporated cathodes is the sharpness of the metal–polymer interface. Liquid metal cathodes result in significantly sharper metal–organic interfaces

  9. Development and optimization of a diode laser for photodynamic therapy.

    Science.gov (United States)

    Lim, Hyun Soo

    2011-01-01

    This study demonstrated the development of a laser system for cancer treatment with photodynamic therapy (PDT) based on a 635 nm laser diode. In order to optimize efficacy in PDT, the ideal laser system should deliver a homogeneous nondivergent light energy with a variable spot size and specific wavelength at a stable output power. We developed a digital laser beam controller using the constant current method to protect the laser diode resonator from the current spikes and other fluctuations, and electrical faults. To improve the PDT effects, the laser system should deliver stable laser energy in continuous wave (CW), burst mode and super burst mode, with variable irradiation times depending on the tumor type and condition. The experimental results showed the diode laser system described herein was eminently suitable for PDT. The laser beam was homogeneous without diverging and the output power increased stably and in a linear manner from 10 mW to 1500 mW according to the increasing input current. Variation between the set and delivered output was less than 7%. The diode laser system developed by the author for use in PDT was compact, user-friendly, and delivered a stable and easily adjustable output power at a specific wavelength and user-set emission modes.

  10. Fiber optic modification of a diode array spectrophotometer

    International Nuclear Information System (INIS)

    Van Hare, D.R.; Prather, W.S.

    1986-01-01

    Fiber optics were adapted to a Hewlett-Packard diode array spectrophotometer to permit the analysis of radioactive samples without risking contamination of the instrument. Instrument performance was not compromised by the fiber optics. The instrument is in routine use at the Savannah River Plant control laboratories

  11. Non-linear thermal fluctuations in a diode

    NARCIS (Netherlands)

    Kampen, N.G. van

    As an example of non-linear noise the fluctuations in a circuit consisting of a diode and a condenser C are studied. From the master equation for this system the following results are derived. 1. (i) The equilibrium distribution of the voltage is rigorously Gaussian, the average voltage being

  12. Application of a diode-array detector in capillary electrophoresis

    NARCIS (Netherlands)

    Beck, W.; Hoek, van R.; Engelhardt, H.

    1993-01-01

    In the last decade diode-array detection has proved to be extremely useful in high performance liquid chromatography in recording UV-visible spectra directly and on-line in the column effluent. In capillary electrophoresis (CE) only fast-scanning detectors with long scan times (up to 2 s) are

  13. Performance enhancement of polymer Schottky diode by doping pentacene

    International Nuclear Information System (INIS)

    Kang, K.S.; Chen, Y.; Lim, H.K.; Cho, K.Y.; Han, K.J.; Kim, Jaehwan

    2009-01-01

    Schottky diodes have been fabricated using pentacene-doped poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) as a semiconducting material. To understand the fundamental properties of the pentacene-doped PEDOT:PSS, ultraviolet visible (UV) absorption spectroscopy was employed. It was found that a significant amount of pentacene can dissolve in n-methylpyrrolidone solvent. No characteristic absorption peak of pentacene was observed in the UV-visible spectra of PEDOT:PSS films doped with pentacene,. However, the absorption intensity of the doped PEDOT:PSS films increased as the pentacene concentration increased in particular in the UV region. The atomic force microscope images show that the surface roughnesses of PEDOT:PSS films increased as the pentacene concentration increased. Three-layer Schottky diodes comprising Al/PEDOT:PSS/Au or Al/PEDOT:PSS-pentacene/Au were fabricated. The maximum forward currents of non-doped and doped Schottky diodes were 4.8 and 440 μA/cm 2 at 3.3 MV/m, respectively. The forward current increased nearly two orders of magnitude for Schottky diode doped with 11.0 wt.% of pentacene.

  14. Two-dimensional ion effects in relativistic diodes

    International Nuclear Information System (INIS)

    Poukey, J.W.

    1975-01-01

    In relativistic diodes, ions are emitted from the anode plasma. The effects and properties of these ions are studied via a two-dimensional particle simulation code. The space charge of these ions enhances the electron emission, and this additional current (including that of the ions, themselves) aids in obtaining superpinched electron beams for use in pellet fusion studies. (U.S.)

  15. Hybrid simulation of electrode plasmas in high-power diodes

    International Nuclear Information System (INIS)

    Welch, Dale R.; Rose, David V.; Bruner, Nichelle; Clark, Robert E.; Oliver, Bryan V.; Hahn, Kelly D.; Johnston, Mark D.

    2009-01-01

    New numerical techniques for simulating the formation and evolution of cathode and anode plasmas have been successfully implemented in a hybrid code. The dynamics of expanding electrode plasmas has long been recognized as a limiting factor in the impedance lifetimes of high-power vacuum diodes and magnetically insulated transmission lines. Realistic modeling of such plasmas is being pursued to aid in understanding the operating characteristics of these devices as well as establishing scaling relations for reliable extrapolation to higher voltages. Here, in addition to kinetic and fluid modeling, a hybrid particle-in-cell technique is described that models high density, thermal plasmas as an inertial fluid which transitions to kinetic electron or ion macroparticles above a prescribed energy. The hybrid technique is computationally efficient and does not require resolution of the Debye length. These techniques are first tested on a simple planar diode then applied to the evolution of both cathode and anode plasmas in a high-power self-magnetic pinch diode. The impact of an intense electron flux on the anode surface leads to rapid heating of contaminant material and diode impedance loss.

  16. Diode laser for the treatment of telangiectasias following hemangioma involution.

    Science.gov (United States)

    Cerrati, Eric W; O, Teresa M; Chung, Hoyun; Waner, Milton

    2015-02-01

    Infantile hemangiomas are well known for their rapid growth during the first 6 to 9 months of life, followed by a spontaneous but slow involution. The standard of care is to treat these lesions at an early age with propranolol to expedite the involution process; however, surgery still remains an active component in the management. Medical treatment with propranolol or natural involution will often result in residual telangiectasias. We evaluated the efficacy of using a diode laser as a treatment for telangiectasias following cervicofacial infantile hemangioma involution. Case series with chart review. Tertiary care hospital and practice specializing in the care of vascular anomalies. Twenty patients, aged 4 months to 11 years (average 2.69 years), underwent treatment with a 532-nm diode laser to treat the residual telangiectasias following hemangioma involution. All procedures were performed in the operating room. To assess the efficacy, we independently evaluated pre- and posttreatment digital photographs and ranked them on a 0- to 4-point scale (0 = no change and 4 = complete response). Adverse reactions were also recorded. The telangiectasias showed considerable improvement following treatment. In more than half of the patients treated, the affected area demonstrated a complete response. No adverse reactions were noted. A 532-nm diode laser effectively treats the remaining telangiectasias following hemangioma involution. Whether used independently or in conjunction with other treatment modalities, the diode laser should be part of the surgical armamentarium when treating infantile hemangiomas. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2014.

  17. Improvement in light-extraction efficiency of light emitting diode ...

    Indian Academy of Sciences (India)

    The effect of various microlens parameters such as diameter and area fraction on light-extraction efficiency was systematically studied. Improvement of 4% in extraction efficiency was obtained by employing it on white light emitting diode. The area fraction of microlenses was increased up to 0.34 by reducing the spin speed.

  18. Fast neutron dosimeter with wide base silicon diode

    International Nuclear Information System (INIS)

    Ma Lu

    1986-01-01

    This paper briefly introduces a wide base silicon diode fast neutron dosimeter with wide measuring range and good energy response to fast neutron. It is suitable to be used to detect fast neutrons in the mixed field of γ-ray, thermal neutrons and fast neutrons

  19. Particle detectors based on InP Schottky diodes

    Czech Academy of Sciences Publication Activity Database

    Yatskiv, Roman; Grym, Jan

    2012-01-01

    Roč. 10, č. 7 (2012), C100051-C100055 ISSN 1748-0221 R&D Projects: GA MŠk(CZ) OC10021; GA MŠk LD12014 Institutional support: RVO:67985882 Keywords : Particle detector * High purity InP layer * Schottky diode Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.869, year: 2011

  20. Design and characterization of single photon avalanche diodes arrays

    Science.gov (United States)

    Neri, L.; Tudisco, S.; Lanzanò, L.; Musumeci, F.; Privitera, S.; Scordino, A.; Condorelli, G.; Fallica, G.; Mazzillo, M.; Sanfilippo, D.; Valvo, G.

    2010-05-01

    During the last years, in collaboration with ST-Microelectronics, we developed a new avalanche photo sensor, single photon avalanche diode (SPAD) see Ref.[S. Privitera, et al., Sensors 8 (2008) 4636 [1];S. Tudisco et al., IEEE Sensors Journal 8 (2008) 1324 [2

  1. Modelling and Simulation of the Diode Split Transformer

    DEFF Research Database (Denmark)

    Østergaard, Leo

    a significant influence on the picture quality. The most critical component is undoubtedly the diode split transformer (DST). Therefore, if developing a simulation model of the DST is possible, a significant step has been taken in the attempt to model the entire horizontal deflection circuit and to obtain...

  2. Improvement in light-extraction efficiency of light emitting diode ...

    Indian Academy of Sciences (India)

    2018-02-02

    Feb 2, 2018 ... emitting diode (OLED) can be enhanced by using light- extraction ... to grow, ω should posses a positive value, which is possible only when ∂φ/∂h < 0, .... To detect small changes, first, the source LED was sta- bilized by ...

  3. Quantum thermal rectification to design thermal diodes and transistors

    Energy Technology Data Exchange (ETDEWEB)

    Joulain, Karl; Ezzahri, Younes; Ordonez-Miranda, Jose [Univ. de Poitiers, Futuroscope Chasseneuil (France). Inst. Pprime, CNRS

    2017-05-01

    We study in this article how heat can be exchanged between two-level systems, each of them being coupled to a thermal reservoir. Calculations are performed solving a master equation for the density matrix using the Born-Markov approximation. We analyse the conditions for which a thermal diode and a thermal transistor can be obtained as well as their optimisation.

  4. Measurement of Phase Dependent Impedance for 3-phase Diode Rectifier

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth

    2016-01-01

    This paper presents a new method to measure the phase dependent impedance from an experimental set up. Though most of power electronics based system is gradually migrating to IGBT based voltage source converter due to their controllability, the rectifier composed of diode or thyristor components...

  5. Frequency Support from OWPPs connected to HVDC via Diode Rectifiers

    DEFF Research Database (Denmark)

    Saborío-Romano, Oscar; Bidadfar, Ali; Göksu, Ömer

    This paper presents a study assessing the actual capability of an offshore wind power plant (offshore WPP, OWPP) to provide frequency support (FS) to an onshore network, when connected through a high-voltage direct-current (HVDC) link having a diode rectifier (DR) offshore terminal and a voltage...

  6. Power blue and green laser diodes and their applications

    Science.gov (United States)

    Hager, Thomas; Strauß, Uwe; Eichler, Christoph; Vierheilig, Clemens; Tautz, Sönke; Brüderl, Georg; Stojetz, Bernhard; Wurm, Teresa; Avramescu, Adrian; Somers, André; Ristic, Jelena; Gerhard, Sven; Lell, Alfred; Morgott, Stefan; Mehl, Oliver

    2013-03-01

    InGaN based green laser diodes with output powers up to 50mW are now well established for variety of applications ranging from leveling to special lighting effects and mobile projection of 12lm brightness. In future the highest market potential for visible single mode profile lasers might be laser projection of 20lm. Therefore direct green single-mode laser diodes with higher power are required. We found that self heating was the limiting factor for higher current operation. We present power-current characteristics of improved R and D samples with up to 200mW in cw-operation. An optical output power of 100mW is reached at 215mA, a current level which is suitable for long term operation. Blue InGaN laser diodes are also the ideal source for phosphor based generation of green light sources of high luminance. We present a light engine based on LARP (Laser Activated Remote Phosphor) which can be used in business projectors of several thousand lumens on screen. We discuss the advantages of a laser based systems in comparison with LED light engines. LARP requires highly efficient blue power laser diodes with output power above 1W. Future market penetration of LARP will require lower costs. Therefore we studied new designs for higher powers levels. R and D chips with power-current characteristics up to 4W in continuous wave operation on C-mount at 25°C are presented.

  7. Anode plasma dynamics in the self-magnetic-pinch diode

    Directory of Open Access Journals (Sweden)

    Nichelle Bruner

    2011-02-01

    Full Text Available The self-magnetic-pinch diode is being developed as an intense electron beam source for pulsed-power-driven x-ray radiography. In high-power operation, the beam electrons desorb contaminants from the anode surface from which positive ions are drawn to the cathode. The counterstreaming electrons and ions establish an equilibrium current. It has long been recognized, however, that expanding electrode plasmas can disrupt this equilibrium and cause rapid reduction of the diode impedance and the radiation pulse. Recently developed numerical techniques, which enable simultaneous modeling of particle currents with 10^{13}  cm^{-3} densities to plasmas of near solid density, are applied to a model of the self-magnetic-pinch diode which includes the formation and evolution of anode surface plasmas. Two mechanisms are shown to cause rapid impedance loss, anode plasma expansion into the anode-cathode (A-K gap, and increased ion space-charge near the cathode surface. The former mechanism dominates for shorter A-K gaps, while the latter dominates for longer gaps. Model results qualitatively reproduce the time-dependent impedances measured for this diode.

  8. Atom probe tomography of a commercial light emitting diode

    International Nuclear Information System (INIS)

    Larson, D J; Prosa, T J; Olson, D; Lawrence, D; Clifton, P H; Kelly, T F; Lefebvre, W

    2013-01-01

    The atomic-scale analysis of a commercial light emitting diode device purchased at retail is demonstrated using a local electrode atom probe. Some of the features are correlated with transmission electron microscopy imaging. Subtle details of the structure that are revealed have potential significance for the design and performance of this device

  9. Electron beam formation in high-current diode

    International Nuclear Information System (INIS)

    Korneev, S.A.

    1981-01-01

    The results of experimental investigation of the electron beam formation in diode with cathode on the base of incomplete discharge over the surface of dielectrics with dielectric penetration epsilon 2 . The measurement of current density distribution over transversal cross section reveals an efficient homogeneity [ru

  10. Efficient diode pumped ytterbium-doped fibre laser

    Czech Academy of Sciences Publication Activity Database

    Harun, S.W.; Paul, M.C.; Moghaddam, M.R.A.; Das, S.; Sen, R.; Dhar, Anirban; Pal, M.; Bhadra, S.K.; Ahmad, H.

    2010-01-01

    Roč. 46, č. 1 (2010), s. 68-69 ISSN 0013-5194 Institutional research plan: CEZ:AV0Z20670512 Keywords : Fibre lasers * Oscillator * Diode-pumped Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.001, year: 2010

  11. Local mechanical stress relaxation of Gunn diodes irradiated by protons

    International Nuclear Information System (INIS)

    Gradoboev, A V; Tesleva, E P

    2017-01-01

    The aim of the work is studying the impact of Gunn diodes thermocompression bonding conditions upon their resistance to being radiated with protons of various energies. It was established that the tough conditions of Gunn diodes thermocompression bonding results in local mechanic stresses introduced into the active layer of the device, reduction of electron mobility because of the faults introduction and, subsequently, to reduction of operating current, power of UHF generation, percentage of qualitative units production and general reduction of production efficiency of the devices with required characteristics. Irradiation of Gunn diodes produced under the tough conditions of thermocompression bonding with protons which energy is (40–60) MeV with an absorbed dose of (1–6)·10 2 Gy does not practically reduce the radiation resistance of Gunn diodes produced with application of the given technique. This technique can be recommended for all semiconductor devices on the base of GaAs, which parameters depend significantly upon the mobility of the electrons, to increase the efficiency of production. (paper)

  12. Performance of injection-limited polymer light-emitting diodes

    NARCIS (Netherlands)

    Blom, P.W.M.; Woudenberg, T.V.; Huiberts, H.; Jabbour, GE; Carter, SA; Kido, J; Lee, ST; Sariciftci, NS

    2002-01-01

    The electro-optical characteristics of a polymer light emitting diode (PLED) with a strongly reduced hole injection have been investigated. The device consists of a poly-p-phenylene vinylene semiconductor with a Ag hole injecting contact, which has an injection barrier of about 1 eV. It is observed

  13. The Light-Emitting Diode as a Light Detector

    Science.gov (United States)

    Baird, William H.; Hack, W. Nathan; Tran, Kiet; Vira, Zeeshan; Pickett, Matthew

    2011-01-01

    A light-emitting diode (LED) and operational amplifier can be used as an affordable method to provide a digital output indicating detection of an intense light source such as a laser beam or high-output LED. When coupled with a microcontroller, the combination can be used as a multiple photogate and timer for under $50. A similar circuit is used…

  14. Simulation of cylindrical Pierce diodes with radial flow

    International Nuclear Information System (INIS)

    Alves, M.V.; Gnavi, G.; Gratton, F.T.; Buenos Aires Univ.

    1996-01-01

    In this paper we study the electron instability and the non linear behaviour of cylindrical Pierce's diodes by particle simulation. We ignore here the ion contribution (ions are fixed at a 1/r density and given a very large mass) to give perspicuity to the electron dynamics, and to facilitate comparison with existing theory. (author). 8 refs., 10 figs

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

    DEFF Research Database (Denmark)

    Mosekilde, Erik; Feldberg, Rasmus; Knudsen, Carsten

    1990-01-01

    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...

  16. Effects of thermal cycling on aluminum metallization of power diodes

    DEFF Research Database (Denmark)

    Brincker, Mads; Pedersen, Kristian Bonderup; Kristensen, Peter Kjær

    2015-01-01

    Reconstruction of aluminum metallization on top of power electronic chips is a well-known wear out phenomenon under power cycling conditions. However, the origins of reconstruction are still under discussion. In the current study, a method for carrying out passive thermal cycling of power diodes...

  17. Computer-Assisted Experiments with a Laser Diode

    Science.gov (United States)

    Kraftmakher, Yaakov

    2011-01-01

    A laser diode from an inexpensive laser pen (laser pointer) is used in simple experiments. The radiant output power and efficiency of the laser are measured, and polarization of the light beam is shown. The "h/e" ratio is available from the threshold of spontaneous emission. The lasing threshold is found using several methods. With a…

  18. Seven-laser diode end-pumped Nd

    International Nuclear Information System (INIS)

    Berger, J.; Welch, D.F.; Streifer, W.; Scifres, D.R.; Smith, J.J.; Hoffman, H.J.; Peisley, D.; Radecki, D.

    1988-01-01

    End pumping of solid-state lasers by single semiconductor laser diode arrays (LDAs) is efficient, but the maximum pump power is limited by the source brightness and matching the TEM/sub 00/ Nd:YAG cavity mode. To increase the output power from a solid-state Nd:YAG laser, one option is to employ a multiplicity of LDA to provide more pump power than is available from a single source. The authors report herein a 660-mW cw TEM/sub 00/ Nd:YAG laser, end-pumped by seven LDA, with bundled optical fibers coupling the light from each diode to the Nd:YAG rod end. The maximum electrical-to-optical conversion efficiency attained was 4.7% at 560-mW Nd:YAG output power. The LDAs (SDL-2430-C, 100 μm wide) were mounted on separate thermoelectric coolers to tune emission wavelength to the Nd:YAG absorption bands. The diodes were operated at their rated output power (50,000 h mean time to failure). The 110/125-μm diam 0.37-N.A. fibers were butt coupled to the lasers and glued together into a hexagonal close pack. The authors have obtained the highest average power demonstrated to date in the TEM/sub 00/ mode from a Nd:YAG laser, reliably end-pumped by multiple laser diodes with good efficiency

  19. 3.1 W narrowband blue external cavity diode laser

    Science.gov (United States)

    Peng, Jue; Ren, Huaijin; Zhou, Kun; Li, Yi; Du, Weichuan; Gao, Songxin; Li, Ruijun; Liu, Jianping; Li, Deyao; Yang, Hui

    2018-03-01

    We reported a high-power narrowband blue diode laser which is suitable for subsequent nonlinear frequency conversion into the deep ultraviolet (DUV) spectral range. The laser is based on an external cavity diode laser (ECDL) system using a commercially available GaN-based high-power blue laser diode emitting at 448 nm. Longitudinal mode selection is realized by using a surface diffraction grating in Littrow configuration. The diffraction efficiency of the grating was optimized by controlling the polarization state of the laser beam incident on the grating. A maximum optical output power of 3.1 W in continuous-wave operation with a spectral width of 60 pm and a side-mode suppression ratio (SMSR) larger than 10 dB at 448.4 nm is achieved. Based on the experimental spectra and output powers, the theoretical efficiency and output power of the subsequent nonlinear frequency conversion were calculated according to the Boyd- Kleinman theory. The single-pass conversion efficiency and output power is expected to be 1.9×10-4 and 0.57 mW, respectively, at the 3.1 W output power of the ECDL. The high-power narrowband blue diode laser is very promising as pump source in the subsequent nonlinear frequency conversion.

  20. Optical diagnosis system for intense electron beam diode plasma

    International Nuclear Information System (INIS)

    Yang Jie; Shu Ting; Zhang Jun; Fan Yuwei; Yang Jianhua; Liu Lie; Yin Yi; Luo Ling

    2012-01-01

    A nanosecond time-resolved imaging platform for diode plasmas diagnostics has been constructed based on the pulsed electron beam accelerator and high speed framing camera (HSFC). The accelerator can provide an electrical pulse with voltages of 200-500 kV, rise-time (from 10% to 90% amplitude) of 25 ns and duration of 110 ns. The diode currents up to kA level can be extracted. The trigger signal for camera was picked up by a water-resistor voltage divider after the main switch of the accelerator, which could avoid the disadvantageous influence of the time jitter caused by the breakdown of the gas gaps. Then the sampled negative electrical pulse was converted into a transistor-transistor logic (TTL) signal (5 V) with rise time of about 1.5 ns and time jitter less than 1 ns via a processor. And this signal was taken as the synchronization time base. According to the working characteristics of the camera, the synchronization scheme relying mainly on electrical pulse delay method supplemented by light signal delay method was determined to make sure that the camera can work synchronously with the light production and transportation from the diode plasma within the time scale of nanosecond. Moreover, shielding and filtering methods were used to restrain the interference on the measurement system from the accelerator. Finally, time resolved 2-D framing images of the diode plasma were acquired. (authors)

  1. Tuning the colour of white polymer light emitting diodes

    NARCIS (Netherlands)

    Kok, M.M. de; Sarfert, W.; Paetzold, R.

    2010-01-01

    Colour tuning of white polymer light emitting diode (LED) light sources can be attained by various methods at various stages in the production process of the lamps and/or by the design of the active material incorporated in the LEDs. In this contribution we will describe the methods and discuss the

  2. Diode-pumped laser with improved pumping system

    Science.gov (United States)

    Chang, Jim J.

    2004-03-09

    A laser wherein pump radiation from laser diodes is delivered to a pump chamber and into the lasing medium by quasi-three-dimensional compound parabolic concentrator light channels. The light channels have reflective side walls with a curved surface and reflective end walls with a curved surface. A flow tube between the lasing medium and the light channel has a roughened surface.

  3. SHORT COMMUNICATION: Transportable Zener-diode Voltage Standard

    Science.gov (United States)

    Karpov, O. V.; Shulga, V. M.; Shakirzyanova, F. R.; Sarandi, A. E.

    1994-01-01

    Five transportable Zener-diode dc voltage standards have been developed, fabricated and investigated at the NPO VNIIFTRI. The standards were designed to transfer the unit of electromotive force (emf) from Josephson reference standards to measuring instruments. Following the results of these investigations, standard N 02 has been used for intercomparison of the Russian Josephson reference standards.

  4. Direct diode lasers with comparable beam quality to fiber, CO2, and solid state lasers

    Science.gov (United States)

    Huang, Robin K.; Chann, Bien; Burgess, James; Kaiman, Michael; Overman, Robert; Glenn, John D.; Tayebati, Parviz

    2012-03-01

    TeraDiode has produced kW-class ultra-high brightness fiber-coupled direct diode lasers. A fiber-coupled direct diode laser with a power level of 2,040 W from a 50 μm core diameter, 0.15 numerical aperture (NA) output fiber at a single center wavelength was demonstrated. This was achieved with a novel beam combining and shaping technique using COTS diode lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 3.75 mm-mrad and is the lowest BPP kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 2-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers.

  5. Light ion source studies with a magnetically insulated extraction diode

    International Nuclear Information System (INIS)

    Struckman, C.K.

    1992-01-01

    Light ion sources are currently being studied to assess their ability to drive an inertial confinement fusion reactor. The author has produced a high purity, 1MV, 300A/cm 2 lithium beam using a 200cm 2 extraction geometry, magnetically insulated ion diode. The lithium source was an AC glow discharge cleaned, LiF/Al film active anode. The active anode plasma was formed after 50KA of current was shunted through the anode film for 20ns. The stoichiometry of the resulting ion beam was 65% Li + , 20% Al +2 , and 15% H + . Without the glow discharge cleaning, the ion beam was over 55% hydrogen and only 20% Li + . At the time of the diode's design, extraction diodes were producing poor ion beams: their current efficiency was only 60-70%, and their extracted ion current was radially nonuniform. This diode was the first high efficiency extraction diode, and produced over 200KA of ions with 80-90% ion current efficiency. In addition, by varying the tilt of the applied magnetic field, it was possible to show that the ion current density could be made independent of radius. Since the author was unable to make a Li + beam with a passive anode, he installed an active anode that used an external current to vaporize a thin metal film on the anode surface. Poor beam purity was the most serious problem with active anodes. In order to remove impurities, especially the hydrogen contamination, the author cleaned the anodes with a glow discharge. Al film anodes were cleaned with a 110mA, 33W DC glow discharge, and the LiF/Al film anodes were cleaned with an equivalent AC discharge. The results obtained and a model for the mechanism behind the cleaning process are throughly discussed

  6. High average power diode pumped solid state lasers for CALIOPE

    International Nuclear Information System (INIS)

    Comaskey, B.; Halpin, J.; Moran, B.

    1994-07-01

    Diode pumping of solid state media offers the opportunity for very low maintenance, high efficiency, and compact laser systems. For remote sensing, such lasers may be used to pump tunable non-linear sources, or if tunable themselves, act directly or through harmonic crystals as the probe. The needs of long range remote sensing missions require laser performance in the several watts to kilowatts range. At these power performance levels, more advanced thermal management technologies are required for the diode pumps. The solid state laser design must now address a variety of issues arising from the thermal loads, including fracture limits, induced lensing and aberrations, induced birefringence, and laser cavity optical component performance degradation with average power loading. In order to highlight the design trade-offs involved in addressing the above issues, a variety of existing average power laser systems are briefly described. Included are two systems based on Spectra Diode Laboratory's water impingement cooled diode packages: a two times diffraction limited, 200 watt average power, 200 Hz multi-rod laser/amplifier by Fibertek, and TRW's 100 watt, 100 Hz, phase conjugated amplifier. The authors also present two laser systems built at Lawrence Livermore National Laboratory (LLNL) based on their more aggressive diode bar cooling package, which uses microchannel cooler technology capable of 100% duty factor operation. They then present the design of LLNL's first generation OPO pump laser for remote sensing. This system is specified to run at 100 Hz, 20 nsec pulses each with 300 mJ, less than two times diffraction limited, and with a stable single longitudinal mode. The performance of the first testbed version will be presented. The authors conclude with directions their group is pursuing to advance average power lasers. This includes average power electro-optics, low heat load lasing media, and heat capacity lasers

  7. The 1/f noise in a p-i-n diode and in a diode laser below threshold

    NARCIS (Netherlands)

    Fronen, R.J.; Hooge, F.N.

    1991-01-01

    --A theoretical treatment is given of number fluctuations induced by mobility fluctuations in the intrinsic region of a p-i-n diode. Mobility fluctuations lead to fluctuations in voltage across the intrinsic region. In the a.c. short-circuit situation, fluctuations across the intrinsic region result

  8. Application of spherical diodes for megavoltage photon beams dosimetry

    International Nuclear Information System (INIS)

    Barbés, Benigno; Azcona, Juan D.; Burguete, Javier; Martí-Climent, Josep M.

    2014-01-01

    Purpose: External beam radiation therapy (EBRT) usually uses heterogeneous dose distributions in a given volume. Designing detectors for quality control of these treatments is still a developing subject. The size of the detectors should be small to enhance spatial resolution and ensure low perturbation of the beam. A high uniformity in angular response is also a very important feature in a detector, because it has to measure radiation coming from all the directions of the space. It is also convenient that detectors are inexpensive and robust, especially to performin vivo measurements. The purpose of this work is to introduce a new detector for measuring megavoltage photon beams and to assess its performance to measure relative dose in EBRT. Methods: The detector studied in this work was designed as a spherical photodiode (1.8 mm in diameter). The change in response of the spherical diodes is measured regarding the angle of incidence, cumulated irradiation, and instantaneous dose rate (or dose per pulse). Additionally, total scatter factors for large and small fields (between 1 × 1 cm 2 and 20 × 20 cm 2 ) are evaluated and compared with the results obtained from some commercially available ionization chambers and planar diodes. Additionally, the over-response to low energy scattered photons in large fields is investigated using a shielding layer. Results: The spherical diode studied in this work produces a high signal (150 nC/Gy for photons of nominal energy of 15 MV and 160 for 6 MV, after 12 kGy) and its angular dependence is lower than that of planar diodes: less than 5% between maximum and minimum in all directions, and 2% around one of the axis. It also has a moderated variation with accumulated dose (about 1.5%/kGy for 15 MV photons and 0.7%/kGy for 6 MV, after 12 kGy) and a low variation with dose per pulse (±0.4%), and its behavior is similar to commercial diodes in total scatter factor measurements. Conclusions: The measurements of relative dose using

  9. Application of spherical diodes for megavoltage photon beams dosimetry.

    Science.gov (United States)

    Barbés, Benigno; Azcona, Juan D; Burguete, Javier; Martí-Climent, Josep M

    2014-01-01

    External beam radiation therapy (EBRT) usually uses heterogeneous dose distributions in a given volume. Designing detectors for quality control of these treatments is still a developing subject. The size of the detectors should be small to enhance spatial resolution and ensure low perturbation of the beam. A high uniformity in angular response is also a very important feature in a detector, because it has to measure radiation coming from all the directions of the space. It is also convenient that detectors are inexpensive and robust, especially to perform in vivo measurements. The purpose of this work is to introduce a new detector for measuring megavoltage photon beams and to assess its performance to measure relative dose in EBRT. The detector studied in this work was designed as a spherical photodiode (1.8 mm in diameter). The change in response of the spherical diodes is measured regarding the angle of incidence, cumulated irradiation, and instantaneous dose rate (or dose per pulse). Additionally, total scatter factors for large and small fields (between 1 × 1 cm(2) and 20 × 20 cm(2)) are evaluated and compared with the results obtained from some commercially available ionization chambers and planar diodes. Additionally, the over-response to low energy scattered photons in large fields is investigated using a shielding layer. The spherical diode studied in this work produces a high signal (150 nC/Gy for photons of nominal energy of 15 MV and 160 for 6 MV, after 12 kGy) and its angular dependence is lower than that of planar diodes: less than 5% between maximum and minimum in all directions, and 2% around one of the axis. It also has a moderated variation with accumulated dose (about 1.5%/kGy for 15 MV photons and 0.7%/kGy for 6 MV, after 12 kGy) and a low variation with dose per pulse (± 0.4%), and its behavior is similar to commercial diodes in total scatter factor measurements. The measurements of relative dose using the spherical diode described in this

  10. Electron beam characterization of a combined diode rf electron gun

    Directory of Open Access Journals (Sweden)

    R. Ganter

    2010-09-01

    Full Text Available Experimental and simulation results of an electron gun test facility, based on pulsed diode acceleration followed by a two-cell rf cavity at 1.5 GHz, are presented here. The main features of this diode-rf combination are: a high peak gradient in the diode (up to 100  MV/m obtained without breakdown conditioning, a cathode shape providing an electrostatic focusing, and an in-vacuum pulsed solenoid to focus the electron beam between the diode and the rf cavity. Although the test stand was initially developed for testing field emitter arrays cathodes, it became also interesting to explore the limits of this electron gun with metallic photocathodes illuminated by laser pulses. The ultimate goal of this test facility is to fulfill the requirements of the SwissFEL project of Paul Scherrer Institute [B. D. Patterson et al., New J. Phys. 12, 035012 (2010NJOPFM1367-263010.1088/1367-2630/12/3/035012]; a projected normalized emittance below 0.4  μm for a charge of 200 pC and a bunch length of less than 10 ps (rms. A normalized projected emittance of 0.23  μm with 13 pC has been measured at 5 MeV using a Gaussian laser longitudinal intensity distribution on the photocathode. Good agreements with simulations have been obtained for different electron bunch charge and diode geometries. Emittance measurements at a bunch charge below 1 pC were performed for different laser spot sizes in agreement with intrinsic emittance theory [e.g. 0.54  μm/mm of laser spot size (rms for Cu at 274 nm]. Finally, a projected emittance of 1.25+/-0.2  μm was measured with 200 pC and 100  MV/m diode gradient.

  11. High-temperature current conduction through three kinds of Schottky diodes

    International Nuclear Information System (INIS)

    Fei, Li; Xiao-Ling, Zhang; Yi, Duan; Xue-Song, Xie; Chang-Zhi, Lü

    2009-01-01

    Fundamentals of the Schottky contacts and the high-temperature current conduction through three kinds of Schottky diodes are studied. N-Si Schottky diodes, GaN Schottky diodes and AlGaN/GaN Schottky diodes are investigated by I–V–T measurements ranging from 300 to 523 K. For these Schottky diodes, a rise in temperature is accompanied with an increase in barrier height and a reduction in ideality factor. Mechanisms are suggested, including thermionic emission, field emission, trap-assisted tunnelling and so on. The most remarkable finding in the present paper is that these three kinds of Schottky diodes are revealed to have different behaviours of high-temperature reverse currents. For the n-Si Schottky diode, a rise in temperature is accompanied by an increase in reverse current. The reverse current of the GaN Schottky diode decreases first and then increases with rising temperature. The AlGaN/GaN Schottky diode has a trend opposite to that of the GaN Schottky diode, and the dominant mechanisms are the effects of the piezoelectric polarization field and variation of two-dimensional electron gas charge density. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  12. Multi-kW high-brightness fiber coupled diode laser based on two dimensional stacked tailored diode bars

    Science.gov (United States)

    Bayer, Andreas; Unger, Andreas; Köhler, Bernd; Küster, Matthias; Dürsch, Sascha; Kissel, Heiko; Irwin, David A.; Bodem, Christian; Plappert, Nora; Kersten, Maik; Biesenbach, Jens

    2016-03-01

    The demand for high brightness fiber coupled diode laser devices in the multi kW power region is mainly driven by industrial applications for materials processing, like brazing, cladding and metal welding, which require a beam quality better than 30 mm x mrad and power levels above 3kW. Reliability, modularity, and cost effectiveness are key factors for success in the market. We have developed a scalable and modular diode laser architecture that fulfills these requirements through use of a simple beam shaping concept based on two dimensional stacking of tailored diode bars mounted on specially designed, tap water cooled heat sinks. The base element of the concept is a tailored diode laser bar with an epitaxial and lateral structure designed such that the desired beam quality in slow-axis direction can be realized without using sophisticated beam shaping optics. The optical design concept is based on fast-axis collimator (FAC) and slow-axis collimator (SAC) lenses followed by only one additional focusing optic for efficient coupling into a 400 μm fiber with a numerical aperture (NA) of 0.12. To fulfill the requirements of scalability and modularity, four tailored bars are populated on a reduced size, tap water cooled heat sink. The diodes on these building blocks are collimated simply via FAC and SAC. The building blocks can be stacked vertically resulting in a two-dimensional diode stack, which enables a compact design of the laser source with minimum beam path length. For a single wavelength, up to eight of these building blocks, implying a total of 32 tailored bars, can be stacked into a submodule, polarization multiplexed, and coupled into a 400 μm, 0.12NA fiber. Scalability into the multi kW region is realized by wavelength combining of replaceable submodules in the spectral range from 900 - 1100 nm. We present results of a laser source based on this architecture with an output power of more than 4 kW and a beam quality of 25 mm x mrad.

  13. Influence of edge roughness on graphene nanoribbon resonant tunnelling diodes

    International Nuclear Information System (INIS)

    Liang Gengchiau; Khalid, Sharjeel Bin; Lam, Kai-Tak

    2010-01-01

    The edge roughness effects of graphene nanoribbons on their application in resonant tunnelling diodes with different geometrical shapes (S, H and W) were investigated. Sixty samples for each 5%, 10% and 15% edge roughness conditions of these differently shaped graphene nanoribbon resonant tunnelling diodes were randomly generated and studied. Firstly, it was observed that edge roughness in the barrier regions decreases the effective barrier height and thickness, which increases the broadening of the quantized states in the quantum well due to the enhanced penetration of the wave-function tail from the electrodes. Secondly, edge roughness increases the effective width of the quantum well and causes the lowering of the quantized states. Furthermore, the shape effects on carrier transport are modified by edge roughness due to different interfacial scattering. Finally, with the effects mentioned above, edge roughness has a considerable impact on the device performance in terms of varying the peak-current positions and degrading the peak-to-valley current ratio.

  14. High current, high bandwidth laser diode current driver

    Science.gov (United States)

    Copeland, David J.; Zimmerman, Robert K., Jr.

    1991-01-01

    A laser diode current driver has been developed for free space laser communications. The driver provides 300 mA peak modulation current and exhibits an optical risetime of less than 400 ps. The current and optical pulses are well behaved and show minimal ringing. The driver is well suited for QPPM modulation at data rates up to 440 Mbit/s. Much previous work has championed current steering circuits; in contrast, the present driver is a single-ended on/off switch. This results in twice the power efficiency as a current steering driver. The driver electrical efficiency for QPPM data is 34 percent. The high speed switch is realized with a Ku-band GaAsFET transistor, with a suitable pre-drive circuit, on a hybrid microcircuit adjacent to the laser diode.

  15. Influence of irradiation on defects creation in pin diode structure

    International Nuclear Information System (INIS)

    Sopko, V.; Dammer, J.; Sopko, B.; Chren, D.

    2012-01-01

    In this paper the manufacture of type S1 PIN diodes and radiation defect induce by fast neutrons were studied. A shift from VV"- to VV (neutral) is observed in neutron irradiated diodes. From the results obtained, an explanation that clearly offers itself is that the nature of the defects produced by irradiation of material exhibiting N type conductivity is different from those for type P material. Given that the experiments were conducted with the same material, i.e., the dopant present in the material remained unchanged, it can be stated that simply by changing the type of conductivity with increasing dose, a different kind of defects is produced, having different activation energies in the forbidden band. All these results are consistent with the ongoing RD 50 experiments at CERN.

  16. Monte Carlo modelling of Schottky diode for rectenna simulation

    Science.gov (United States)

    Bernuchon, E.; Aniel, F.; Zerounian, N.; Grimault-Jacquin, A. S.

    2017-09-01

    Before designing a detector circuit, the electrical parameters extraction of the Schottky diode is a critical step. This article is based on a Monte-Carlo (MC) solver of the Boltzmann Transport Equation (BTE) including different transport mechanisms at the metal-semiconductor contact such as image force effect or tunneling. The weight of tunneling and thermionic current is quantified according to different degrees of tunneling modelling. The I-V characteristic highlights the dependence of the ideality factor and the current saturation with bias. Harmonic Balance (HB) simulation on a rectifier circuit within Advanced Design System (ADS) software shows that considering non-linear ideality factor and saturation current for the electrical model of the Schottky diode does not seem essential. Indeed, bias independent values extracted in forward regime on I-V curve are sufficient. However, the non-linear series resistance extracted from a small signal analysis (SSA) strongly influences the conversion efficiency at low input powers.

  17. Analytic formalism for current crowding in light emitting diodes

    International Nuclear Information System (INIS)

    Lee, Kyu-Seok

    2012-01-01

    This paper presents an analytic approach to simulating current crowding (CC) in light-emitting diodes with parallel p- and n-contacts. The electrical potential difference across the p-i-n layers is derived from the Laplace equation, whereas the current density through the p-i-n layers is obtained from the current density - voltage relation of a single-diode model. Since these two properties influence each other, they are calculated iteratively. It is found that CC depends on the applied voltage (or the average current density), the sheet resistances of the p- and the n-contact layers, the width of the active region, and the specific series resistance and ideality factor of the p-i-n layers. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Charge Transport in 2D DNA Tunnel Junction Diodes

    KAUST Repository

    Yoon, Minho

    2017-11-06

    Recently, deoxyribonucleic acid (DNA) is studied for electronics due to its intrinsic benefits such as its natural plenitude, biodegradability, biofunctionality, and low-cost. However, its applications are limited to passive components because of inherent insulating properties. In this report, a metal-insulator-metal tunnel diode with Au/DNA/NiOx junctions is presented. Through the self-aligning process of DNA molecules, a 2D DNA nanosheet is synthesized and used as a tunneling barrier, and semitransparent conducting oxide (NiOx ) is applied as a top electrode for resolving metal penetration issues. This molecular device successfully operates as a nonresonant tunneling diode, and temperature-variable current-voltage analysis proves that Fowler-Nordheim tunneling is a dominant conduction mechanism at the junctions. DNA-based tunneling devices appear to be promising prototypes for nanoelectronics using biomolecules.

  19. Diode laser for excisional biopsy of peripheral ossifying fibroma

    Directory of Open Access Journals (Sweden)

    Kirti Chawla

    2014-01-01

    Full Text Available Peripheral Ossifying Fibroma is one of the commonest occurring reactive lesions on gingiva. It is associated with local irritational factors and often interferes with speech, mastication and maintenance of oral hygiene, in addition to being aesthetically unpleasant. It is usually treated with surgical excision using scalpel and removal of irritational factors, often resulting in mucogingival defect. Other modalities such as radiosurgery and electrocautery have also been used for its management, but they cause changes in microarchitecture of biopsy specimen, altering the histologic picture for true diagnosis. We are presenting a case of excisional biopsy of this lesion in an adult female using a diode laser with excellent post-operative results, without affecting microarchitecture of biopsy specimen. The patient is being followed for last 1 year and no sign of recurrence has been found. A diode laser may offer a good alternative modality for management of such cases.

  20. Transscleral diode photocoagulation of large retinal and choroidal vascular lesions.

    Directory of Open Access Journals (Sweden)

    Yun Feng

    Full Text Available BACKGROUND: Transscleral retinal photocoagulation with a diode laser is used in glaucoma refractory to medical and surgical treatment. Our main research question was how the technique performed in large vascular lesions associated with hemangiomas of the retina and choroid. METHODOLOGY/CLINICAL FINDINGS: Patient charts were retrieved from the hospital files for patients who underwent the procedure and were followed for at least 24 months. Five patients (6 eyes fit the criteria. Cases included Von Hippel's disease (2 eyes, Coats' disease (1 eye and choroidal hemangioma (3 cases. Transscleral diode laser treatment was performed under retrobulbar and topical anesthesia with a retinopexy probe (IRIS DioPexy, IRIS Medical Instruments, Mountain View, CA applied transsclerally under indirect ophthalmoscope visualization. We found an improvement in best-corrected visual acuity at 24 months postoperatively. CONCLUSIONS/SIGNIFICANCE: Transscleral photocoagulation may have a clinical application in these diseases as an alternate to the high cost of photodynamic therapy with photosensitizing agents.

  1. Management of gingival hyperpigmentation by semiconductor diode laser

    Directory of Open Access Journals (Sweden)

    Geeti Gupta

    2011-01-01

    Full Text Available Gingival hyperpigmentation is caused by excessive deposition of melanin in the basal and suprabasal cell layers of the epithelium. Although melanin pigmentation of the gingiva is completely benign, cosmetic concerns are common, particularly in patients having a very high smile line (gummy smile. Various depigmentation techniques have been employed, such as scalpel surgery, gingivectomy, gingivectomy with free gingival autografting, cryosurgery, electrosurgery, chemical agents such as 90% phenol and 95% alcohol, abrasion with diamond burs, Nd:YAG laser, semiconductor diode laser, and CO 2 laser. The present case report describes simple and effective depigmentation technique using semiconductor diode laser surgery - for gingival depigmentation, which have produced good results with patient satisfaction.

  2. Oxygen measurement by multimode diode lasers employing gas correlation spectroscopy.

    Science.gov (United States)

    Lou, Xiutao; Somesfalean, Gabriel; Chen, Bin; Zhang, Zhiguo

    2009-02-10

    Multimode diode laser (MDL)-based correlation spectroscopy (COSPEC) was used to measure oxygen in ambient air, thereby employing a diode laser (DL) having an emission spectrum that overlaps the oxygen absorption lines of the A band. A sensitivity of 700 ppm m was achieved with good accuracy (2%) and linearity (R(2)=0.999). For comparison, measurements of ambient oxygen were also performed by tunable DL absorption spectroscopy (TDLAS) technique employing a vertical cavity surface emitting laser. We demonstrate that, despite slightly degraded sensitivity, the MDL-based COSPEC-based oxygen sensor has the advantages of high stability, low cost, ease-of-use, and relaxed requirements in component selection and instrument buildup compared with the TDLAS-based instrument.

  3. Electron diode oscillators for high-power RF generation

    International Nuclear Information System (INIS)

    Humphries, S.

    1989-01-01

    Feedback oscillators have been used since the invention of the vacuum tube. This paper describes the extension of these familiar circuits to the regime of relativistic electron beam diodes. Such devices have potential application for the generation of high power RF radiation in the range 50-250 MHz, 1-10 GW with 20-60% conversion efficiency. This paper reviews the theory of the oscillator and the results of a design study. Calculations for the four-electrode diode with EGUN and EBQ show that good modulations of 30 kA electron beam at 600 kV can be achieved with moderate field stress on the electrodes. Conditions for oscillation have been studied with an in-house transmission line code. A design for a 7.5 GW oscillator at 200 MHz with 25% conversion efficiency is presented

  4. High brightness diode-pumped organic solid-state laser

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zhuang; Mhibik, Oussama; Nafa, Malik; Chénais, Sébastien; Forget, Sébastien, E-mail: sebastien.forget@univ-paris13.fr [Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, F-93430, Villetaneuse (France); CNRS, UMR 7538, LPL, F-93430, Villetaneuse (France)

    2015-02-02

    High-power, diffraction-limited organic solid-state laser operation has been achieved in a vertical external cavity surface-emitting organic laser (VECSOL), pumped by a low-cost compact blue laser diode. The diode-pumped VECSOLs were demonstrated with various dyes in a polymer matrix, leading to laser emissions from 540 nm to 660 nm. Optimization of both the pump pulse duration and output coupling leads to a pump slope efficiency of 11% for a DCM based VECSOLs. We report output pulse energy up to 280 nJ with 100 ns long pump pulses, leading to a peak power of 3.5 W in a circularly symmetric, diffraction-limited beam.

  5. Specifies of the formed fast cover silica diodes

    Directory of Open Access Journals (Sweden)

    Gorban A. N.,

    2008-06-01

    Full Text Available The authors have investigated the dependence of the current recovery time trr on the diode structures annealing parameters after irradiation by electrons е– with the energy of 4 and 10 MeV, and the fluence of 6•1015 and 8•1014 cm–2, respectively. Diodes with minimal time trr and maximum shape factor of the reduction current Krr are obtained by annealing of structures after irradiation by е– with the energy of 4 MeV and fluence 6•1015 cm–2. Time trr decreases with the increase of ratio of recombination centers concentration with energy level E3(0,37 to the concentration of other defects. At the same time, for silicon, doped with transmutation nuclear reactions, it is necessary to increase the annealing temperature as compared with the silicon, produced by the Czochralski method and zone melting method.

  6. Quench Propagation Ignition using Single-Mode Diode Laser

    CERN Document Server

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

    2005-01-01

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

  7. Unidirectional oxide hetero-interface thin-film diode

    International Nuclear Information System (INIS)

    Park, Youngmin; Lee, Eungkyu; Lee, Jinwon; Lim, Keon-Hee; Kim, Youn Sang

    2015-01-01

    The unidirectional thin-film diode based on oxide hetero-interface, which is well compatible with conventional thin-film fabrication process, is presented. With the metal anode/electron-transporting oxide (ETO)/electron-injecting oxide (EIO)/metal cathode structure, it exhibits that electrical currents ohmically flow at the ETO/EIO hetero-interfaces for only positive voltages showing current density (J)-rectifying ratio of ∼10 5 at 5 V. The electrical properties (ex, current levels, and working device yields) of the thin-film diode (TFD) are systematically controlled by changing oxide layer thickness. Moreover, we show that the oxide hetero-interface TFD clearly rectifies an AC input within frequency (f) range of 10 2  Hz < f < 10 6  Hz, providing a high feasibility for practical applications

  8. Unidirectional oxide hetero-interface thin-film diode

    Energy Technology Data Exchange (ETDEWEB)

    Park, Youngmin; Lee, Eungkyu; Lee, Jinwon; Lim, Keon-Hee [Program in Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 151-742 (Korea, Republic of); Kim, Youn Sang, E-mail: younskim@snu.ac.kr [Program in Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 151-742 (Korea, Republic of); Advanced Institute of Convergence Technology, Gyeonggi-do 443-270 (Korea, Republic of)

    2015-10-05

    The unidirectional thin-film diode based on oxide hetero-interface, which is well compatible with conventional thin-film fabrication process, is presented. With the metal anode/electron-transporting oxide (ETO)/electron-injecting oxide (EIO)/metal cathode structure, it exhibits that electrical currents ohmically flow at the ETO/EIO hetero-interfaces for only positive voltages showing current density (J)-rectifying ratio of ∼10{sup 5} at 5 V. The electrical properties (ex, current levels, and working device yields) of the thin-film diode (TFD) are systematically controlled by changing oxide layer thickness. Moreover, we show that the oxide hetero-interface TFD clearly rectifies an AC input within frequency (f) range of 10{sup 2} Hz < f < 10{sup 6} Hz, providing a high feasibility for practical applications.

  9. Production of annular electron beams by foilless diodes

    International Nuclear Information System (INIS)

    Miller, R.B.; Prestwich, K.R.; Poukey, J.W.; Shope, S.L.

    1980-01-01

    A number of important aspects of the production of annular electron beams by foilless diodes are examined, both theoretically and experimentally. The theories of Ott, Antonsen, and Lovelace (OAL) and Chen and Lovelace (CL) are compared, and the CL theory is extended to include the effect of an axial gap in an approximate fashion. For the case of finite magnetic field strengths, Larmor orbits are examined and radial oscillations of the beam profile are predicted from a beam envelope analysis. Experimental results obtained with both low- and high-impedance sources have been compared with the theory, and based on such studies, the design and construction of an intense hollow beam generator are described. Experimental results obtained with the new diode compare favorably with both the analytic theory and the results of numerical simulations. The device currently produces 2-MeV electrons at beam currents of 65--70 kA

  10. Thermally stimulated current method applied to highly irradiated silicon diodes

    CERN Document Server

    Pintilie, I; Pintilie, I; Moll, Michael; Fretwurst, E; Lindström, G

    2002-01-01

    We propose an improved method for the analysis of Thermally Stimulated Currents (TSC) measured on highly irradiated silicon diodes. The proposed TSC formula for the evaluation of a set of TSC spectra obtained with different reverse biases leads not only to the concentration of electron and hole traps visible in the spectra but also gives an estimation for the concentration of defects which not give rise to a peak in the 30-220 K TSC temperature range (very shallow or very deep levels). The method is applied to a diode irradiated with a neutron fluence of phi sub n =1.82x10 sup 1 sup 3 n/cm sup 2.

  11. Laser diode self-mixing technique for liquid velocimetry

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrova, A., E-mail: a.alexandrova@liverpool.ac.uk [Cockcroft Institute, Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); University of Liverpool, Department of Physics, Liverpool L69 7ZE (United Kingdom); Welsch, C.P. [Cockcroft Institute, Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); University of Liverpool, Department of Physics, Liverpool L69 7ZE (United Kingdom)

    2016-09-11

    Using the self-mixing technique, or optical feedback interferometry, fluid velocity measurements of water seeded with titanium dioxide have been performed using a laser diode to measure the effect of the seeding particle concentration and also the pump speed of the flow. The velocimeter utilises commercially available laser diodes with a built-in photodiode for detection of the self-mixing effect. The device has demonstrated an accuracy better than 10% for liquid flow velocities up to 1.5 m/s with a concentration of scattering particles in the range of 0.8–0.03%. This is an improvement of one order of magnitude compared to previous experiments. The proposed velocimeter is to be developed further for application in gas-jet measurements.

  12. Dye-enhanced diode laser photocoagulation of choroidal neovascularizations

    Science.gov (United States)

    Klingbeil, Ulrich; Puliafito, Carmen A.; McCarthy, Dan; Reichel, Elias; Olk, Joseph; Lesiecki, Michael L.

    1994-06-01

    Dye-enhanced diode laser photocoagulation, using the dye indocyanine green (ICG), has shown some potential in the treatment of choroidal neovascularizations (CNV). A diode laser system was developed and optimized to emit at the absorption maximum of ICG. In a clinical study at two retinal centers, more than 70 patients, the majority of which had age-related macular degeneration, were treated. Eighteen cases with ill-defined subfoveal CNV were followed an average of 11 months after laser treatment. The results show success in resolving the CNV with an average long-term preservation of visual function equal to or superior to data provided by the Macular Photocoagulation Study for confluent burns of low intensity applied to the CNV. Details of the technique and discussion of the controversies inherent in such a treatment strategy will be presented.

  13. Mode-locked solid state lasers using diode laser excitation

    Science.gov (United States)

    Holtom, Gary R [Boston, MA

    2012-03-06

    A mode-locked laser employs a coupled-polarization scheme for efficient longitudinal pumping by reshaped laser diode bars. One or more dielectric polarizers are configured to reflect a pumping wavelength having a first polarization and to reflect a lasing wavelength having a second polarization. An asymmetric cavity provides relatively large beam spot sizes in gain medium to permit efficient coupling to a volume pumped by a laser diode bar. The cavity can include a collimation region with a controlled beam spot size for insertion of a saturable absorber and dispersion components. Beam spot size is selected to provide stable mode locking based on Kerr lensing. Pulse durations of less than 100 fs can be achieved in Yb:KGW.

  14. Cathode plasma expansion in diode with explosive emission

    International Nuclear Information System (INIS)

    Zuo Yinghong; Fan Ruyu; Wang Jianguo; Zhu Jinhui

    2012-01-01

    The evolution characteristics of the cathode plasma in a planar diode with explosive emission were analyzed. Be- sides the axial expansion which can reduce the effective anode-cathode gap, the radial expansion of the cathode plasma which can affect the effective emitting area was also taken into account. According to the Child-Langmuir law and the experimental data of current and voltage with a electron vacuum diode under four-pulse mode, the dynamics of the cathode plasma was investigated, on the assumption that the radial speeds of the cathode plasma was approximately equal to the axial speed. The results show that the radial and axial expansion speeds of the cathode plasma are 0.9-2.8 cm/μs. (authors)

  15. Charge Transport in 2D DNA Tunnel Junction Diodes

    KAUST Repository

    Yoon, Minho; Min, Sung-Wook; Dugasani, Sreekantha Reddy; Lee, Yong Uk; Oh, Min Suk; Anthopoulos, Thomas D.; Park, Sung Ha; Im, Seongil

    2017-01-01

    Recently, deoxyribonucleic acid (DNA) is studied for electronics due to its intrinsic benefits such as its natural plenitude, biodegradability, biofunctionality, and low-cost. However, its applications are limited to passive components because of inherent insulating properties. In this report, a metal-insulator-metal tunnel diode with Au/DNA/NiOx junctions is presented. Through the self-aligning process of DNA molecules, a 2D DNA nanosheet is synthesized and used as a tunneling barrier, and semitransparent conducting oxide (NiOx ) is applied as a top electrode for resolving metal penetration issues. This molecular device successfully operates as a nonresonant tunneling diode, and temperature-variable current-voltage analysis proves that Fowler-Nordheim tunneling is a dominant conduction mechanism at the junctions. DNA-based tunneling devices appear to be promising prototypes for nanoelectronics using biomolecules.

  16. Treatment of Gingival Hyperpigmentation by Diode Laser for Esthetical Purposes

    Directory of Open Access Journals (Sweden)

    Hanaa M. El Shenawy

    2015-08-01

    Full Text Available BACKGROUND: Gingival hyperpigmentation is a common esthetical concern in patients with gummy smile or excessive gingival display. Laser ablation has been recognized recently as the most effective, pleasant and reliable technique. It has the advantage of easy handling, short treatment time, hemostasis, decontamination, and sterilization effect. AIM: In the present study we wanted to explore the efficacy of a 980 nm wavelength diode laser in gingival depigmentation clinically by using both VAS and digital imaging method as means of assessment. METHODS: Diode laser ablation was done for 15 patients who requested cosmetic therapy for melanin pigmented gums. The laser beam delivered by fiberoptic with a diameter of 320 µm, the diode laser system has 980 nm wave lengths and 3 W irradiation powers, in a continuous contact mode in all cases, the entire surface of each pigmented maxillary and mandibular gingiva that required treatment was irradiated in a single session. Clinical examination and digital image analysis were done and the patients were followed up for 3 successive months. RESULTS: There was a statistically significant change in prevalence of bleeding after treatment, as none of the cases showed any signs of bleeding 1 week, 1 month and 3 months after ablation. No statistically significant change was observed in the prevalence of swelling after treatment The VAS evaluation demonstrated that only 4 patients complained of mild pain immediately after the procedure. No pain was perceived from the patients in the rest of the follow up period. There was no statistically significant change in prevalence of pain immediately after treatment compared to pain during treatment. There was a decrease in cases with mild pain after 1 week, 1 month as well as 3 months compared to pain during treatment and immediately after treatment. CONCLUSION: Within the limitations of this study, the use of diode laser was shown to be a safe and effective treatment

  17. Radiation effects on breakdown in silicon multiguarded diodes

    International Nuclear Information System (INIS)

    Bisello, D.; Da Rold, M.; Franzin, L.; Wheadon, R.

    1996-01-01

    The authors have investigated the current-voltage characteristics of silicon PIN diodes with a number of different multiguard structures. These structures were designed to increase the overall device breakdown voltage. The same measurements were carried out after gamma irradiation at different doses and neutron irradiation at fluences beyond type-inversion. This study is a first step towards defining guard structures optimized for operation in high-radiation environments such as those expected at the LHC

  18. Light emitting diodes for today's energy conscious world

    Energy Technology Data Exchange (ETDEWEB)

    Papanier, J

    2000-10-01

    The role played by light emitting diodes in back lighting, decorative illumination, emergency lighting, and automated signage are described as indicators of the many benefits and advantages of LED technology. The basic principles underlying the functioning of LEDs are explained, including the reasons behind their high efficiency in applications requiring colour. The difference between wattage and lumens is clarified; wattage refers to power consumption, whereas lumens measure brightness or light output, the measure most significant in the case of LEDs.

  19. Highly-reliable laser diodes and modules for spaceborne applications

    Science.gov (United States)

    Deichsel, E.

    2017-11-01

    Laser applications become more and more interesting in contemporary missions such as earth observations or optical communication in space. One of these applications is light detection and ranging (LIDAR), which comprises huge scientific potential in future missions. The Nd:YAG solid-state laser of such a LIDAR system is optically pumped using 808nm emitting pump sources based on semiconductor laser-diodes in quasi-continuous wave (qcw) operation. Therefore reliable and efficient laser diodes with increased output powers are an important requirement for a spaceborne LIDAR-system. In the past, many tests were performed regarding the performance and life-time of such laser-diodes. There were also studies for spaceborne applications, but a test with long operation times at high powers and statistical relevance is pending. Other applications, such as science packages (e.g. Raman-spectroscopy) on planetary rovers require also reliable high-power light sources. Typically fiber-coupled laser diode modules are used for such applications. Besides high reliability and life-time, designs compatible to the harsh environmental conditions must be taken in account. Mechanical loads, such as shock or strong vibration are expected due to take-off or landing procedures. Many temperature cycles with high change rates and differences must be taken in account due to sun-shadow effects in planetary orbits. Cosmic radiation has strong impact on optical components and must also be taken in account. Last, a hermetic sealing must be considered, since vacuum can have disadvantageous effects on optoelectronics components.

  20. Diode Laser Velocity Measurements by Modulated Filtered Rayleigh Scattering

    Science.gov (United States)

    Mach, J. J.; Varghese, P. L.; Jagodzinski, J. J.

    1999-01-01

    The ability of solid-state lasers to be tuned in operating frequency at MHz rates by input current modulation, while maintaining a relatively narrow line-width, has made them useful for spectroscopic measurements. Their other advantages include low cost, reliability, durability, compact size, and modest power requirements, making them a good choice for a laser source in micro-gravity experiments in drop-towers and in flight. For their size, they are also very bright. In a filtered Rayleigh scattering (FRS) experiment, a diode laser can be used to scan across an atomic or molecular absorption line, generating large changes in transmission at the resonances for very small changes in frequency. The hyperfine structure components of atomic lines of alkali metal vapors are closely spaced and very strong, which makes such atomic filters excellent candidates for sensitive Doppler shift detection and therefore for high-resolution velocimetry. In the work we describe here we use a Rubidium vapor filter, and work with the strong D(sub 2) transitions at 780 nm that are conveniently accessed by near infrared diode lasers. The low power output of infrared laser diodes is their primary drawback relative to other laser systems commonly used for velocimetry. However, the capability to modulate the laser frequency rapidly and continuously helps mitigate this. Using modulation spectroscopy and a heterodyne detection scheme with a lock-in amplifier, one can extract sub-microvolt signals occurring at a specific frequency from a background that is orders of magnitude stronger. The diode laser modulation is simply achieved by adding a small current modulation to the laser bias current. It may also be swept repetitively in wavelength using an additional lower frequency current ramp.

  1. Large-signal modeling method for power FETs and diodes

    Energy Technology Data Exchange (ETDEWEB)

    Sun Lu; Wang Jiali; Wang Shan; Li Xuezheng; Shi Hui; Wang Na; Guo Shengping, E-mail: sunlu_1019@126.co [School of Electromechanical Engineering, Xidian University, Xi' an 710071 (China)

    2009-06-01

    Under a large signal drive level, a frequency domain black box model of the nonlinear scattering function is introduced into power FETs and diodes. A time domain measurement system and a calibration method based on a digital oscilloscope are designed to extract the nonlinear scattering function of semiconductor devices. The extracted models can reflect the real electrical performance of semiconductor devices and propose a new large-signal model to the design of microwave semiconductor circuits.

  2. Large-signal modeling method for power FETs and diodes

    International Nuclear Information System (INIS)

    Sun Lu; Wang Jiali; Wang Shan; Li Xuezheng; Shi Hui; Wang Na; Guo Shengping

    2009-01-01

    Under a large signal drive level, a frequency domain black box model of the nonlinear scattering function is introduced into power FETs and diodes. A time domain measurement system and a calibration method based on a digital oscilloscope are designed to extract the nonlinear scattering function of semiconductor devices. The extracted models can reflect the real electrical performance of semiconductor devices and propose a new large-signal model to the design of microwave semiconductor circuits.

  3. Diode lasers optimized in brightness for fiber laser pumping

    Science.gov (United States)

    Kelemen, M.; Gilly, J.; Friedmann, P.; Hilzensauer, S.; Ogrodowski, L.; Kissel, H.; Biesenbach, J.

    2018-02-01

    In diode laser applications for fiber laser pumping and fiber-coupled direct diode laser systems high brightness becomes essential in the last years. Fiber coupled modules benefit from continuous improvements of high-power diode lasers on chip level regarding output power, efficiency and beam characteristics resulting in record highbrightness values and increased pump power. To gain high brightness not only output power must be increased, but also near field widths and far field angles have to be below a certain value for higher power levels because brightness is proportional to output power divided by beam quality. While fast axis far fields typically show a current independent behaviour, for broadarea lasers far-fields in the slow axis suffer from a strong current and temperature dependence, limiting the brightness and therefore their use in fibre coupled modules. These limitations can be overcome by carefully optimizing chip temperature, thermal lensing and lateral mode structure by epitaxial and lateral resonator designs and processing. We present our latest results for InGaAs/AlGaAs broad-area single emitters with resonator lengths of 4mm emitting at 976nm and illustrate the improvements in beam quality over the last years. By optimizing the diode laser design a record value of the brightness for broad-area lasers with 4mm resonator length of 126 MW/cm2sr has been demonstrated with a maximum wall-plug efficiency of more than 70%. From these design also pump modules based on 9 mini-bars consisting of 5 emitters each have been realized with 360W pump power.

  4. Online analysis by a fiber-optic diode array spectrophotometer

    International Nuclear Information System (INIS)

    Van Hare, D.R.; Prather, W.S.; O'Rourke, P.E.

    1987-01-01

    An online photometric analyzer has been developed which can make remote measurements over the 350 to 900 nm region at distances of up to 100 feet. The analyzer consists of a commercially available diode array spectrophotometer interfaced to a fiber-optic multiplexer to allow online monitoring of up to ten locations sequentially. The development of the fiber-optic interface is discussed and data from several online applications are presented to demonstrate the capabilities of the measurement system

  5. Diode laser excited optogalvanic spectroscopy of glow discharges

    International Nuclear Information System (INIS)

    Barshick, C. M.; Shaw, R. W.; Jennings, L. W.; Post-Zwicker, A.; Young, J. P.; Ramsey, J. M.

    1997-01-01

    The development of diode-laser-excited isotopically-selective optogalvanic spectroscopy (OGS) of uranium metal, oxide and fluoride in a glow discharge (GD) is presented. The technique is useful for determining 235 U/( 235 U+ 238 U) isotope ratios in these samples. The precision and accuracy of this determination is evaluated, and a study of experimental parameters pertaining to optimization of the measurement is discussed. Application of GD-OGS to other f-transition elements is also described

  6. Diode laser excited optogalvanic spectroscopy of glow discharges

    International Nuclear Information System (INIS)

    Barshick, C.M.; Shaw, R.W.; Post-Zwicker, A., Young, J.P.; Ramsey, J.M.

    1996-01-01

    The development of diode-laser-excited isotopically-selective optogalvanic spectroscopy (OGS) of uranium metal, oxide and fluoride in a glow discharge (GD) is presented. The technique is useful for determining isotopic ratios of 235 U/( 235 U + 238 U) in the above samples. The precision and accuracy of this determination is evaluated, and a study of experimental parameters pertaining to optimization of he measurement is discussed. Application of the GD-OGS to other f-transition elements is also described

  7. Excision of Mucocele Using Diode Laser in Lower Lip

    Directory of Open Access Journals (Sweden)

    Subramaniam Ramkumar

    2016-01-01

    Full Text Available Mucoceles are nonneoplastic cystic lesions of major and minor salivary glands which result from the accumulation of mucus. These lesions are most commonly seen in children. Though usually these lesions can be treated by local surgical excision, in our case, to avoid intraoperative surgical complications like bleeding and edema and to enable better healing, excision was done using a diode laser in the wavelength of 940 nm.

  8. Diode lasers: A magical wand to an orthodontic practice

    Directory of Open Access Journals (Sweden)

    Vipul Kumar Srivastava

    2014-01-01

    Full Text Available LASER (Light Amplification by Stimulated Emission of Radiation is a powerful source of light, which has innumerable applications in all the fields of science including medicine and dentistry. It is one such technology that has become a desirable and an inseparable alternative to many traditional surgical procedures being held in the field of dentistry, and orthodontics is no exception. The current article describes the uses of a diode laser as an indispensable tool in an orthodontic office.

  9. Transient currents in a molecular photo-diode

    OpenAIRE

    Petrov, E. G.; Leonov, V. O.; May, V.; Hänggi, P.

    2012-01-01

    Light-induced charge transmission through a molecular junction (molecular diode) is studied in the framework of a HOMO-LUMO model and in using a kinetic description. Expressions are presented for the sequential (hopping) and direct (tunneling) transient current components together with kinetic equations governing the time-dependent populations of the neutral and charged molecular states which participate in the current formation. Resonant and off-resonant charge transmission processes are ana...

  10. Dual wavelength operation in diode-end-pumped hybrid vanadate ...

    Indian Academy of Sciences (India)

    Dual wavelength operation at 1062.8 nm and 1064.1 nm in a diode-pumped hybrid laser comprising of Nd3+-doped birefringent YVO4 and GdVO4 crystals is demon-strated. A detailed characterization of the laser is performed under CW and pulsed operation. Under Q-switching, 4 W of average power at 5 kHz repetition ...

  11. Study of bypass diodes configuration on PV modules

    Energy Technology Data Exchange (ETDEWEB)

    Silvestre, S.; Boronat, A.; Chouder, A. [Electronics Engineering Department - UPC., C/Jordi Girona 1-3, Modul C4 Campus Nord UPC., 08034 Barcelona (Spain)

    2009-09-15

    A procedure of simulation and modelling solar cells and PV modules, working partially shadowed in Pspice environment, is presented. Simulation results have been contrasted with real measured data from a commercial PV module of 209 Wp from Siliken. Some cases of study are presented as application examples of this simulation methodology, showing its potential on the design of bypass diodes configuration to include in a PV module and also on the study of PV generators working in partial shading conditions. (author)

  12. Remote optically-tunable transimpedance amplifiers for quantum well diodes

    Energy Technology Data Exchange (ETDEWEB)

    Carraresi, L.; Landi, G.; Rocchi, S.; Vignoli, V

    1999-08-01

    In a previous paper we discussed the advantages in using linear optical transmission systems based on quantum well diodes in modern high energy physics experiments. In this paper, after a short summary of the quantum well theory, the electronics section of the above optical transmission system is presented. In particular the basic configuration of a transimpedance amplifier and the arrangement of an optical remote control system for the amplifier gain and bandwidth tuning are discussed.

  13. Remote optically-tunable transimpedance amplifiers for quantum well diodes

    International Nuclear Information System (INIS)

    Carraresi, L.; Landi, G.; Rocchi, S.; Vignoli, V.

    1999-01-01

    In a previous paper we discussed the advantages in using linear optical transmission systems based on quantum well diodes in modern high energy physics experiments. In this paper, after a short summary of the quantum well theory, the electronics section of the above optical transmission system is presented. In particular the basic configuration of a transimpedance amplifier and the arrangement of an optical remote control system for the amplifier gain and bandwidth tuning are discussed

  14. Gaas Displacement Damage Dosimeter Based on Diode Dark Currents

    Directory of Open Access Journals (Sweden)

    Warner Jeffrey H.

    2017-01-01

    Full Text Available GaAs diode dark currents are correlated over a very large proton energy range as a function of displacement damage dose (DDD. The linearity of the dark current increase with DDD over a wide range of applied voltage bias deems this device an excellent candidate for a displacement damage dosimeter. Additional proton testing performed in situ enabled error estimate determination to within 10% for simulated space use.

  15. Minimum ionizing particle detection using amorphous silicon diodes

    Energy Technology Data Exchange (ETDEWEB)

    Xi, J.; Hollingsworth, R.E.; Buitrago, R.H. (Glasstech Solar, Inc., Wheat Ridge, CO (USA)); Oakley, D.; Cumalat, J.P.; Nauenberg, U. (Colorado Univ., Boulder (USA). Dept. of Physics); McNeil, J.A. (Colorado School of Mines, Golden (USA). Dept. of Physics); Anderson, D.F. (Fermi National Accelerator Lab., Batavia, IL (USA)); Perez-Mendez, V. (Lawrence Berkeley Lab., CA (USA))

    1991-03-01

    Hydrogenated amorphous silicon pin diodes have been used to detect minimum ionizing electrons with a pulse height signal-to-noise ratio exceeding 3. A distinct signal was seen for shaping times from 100 to 3000 ns. The devices used had a 54 {mu}m thick intrinsic layer and an active area of 0.1 cm{sup 2}. The maximum signal was 3200 electrons with a noise width of 950 electrons for a shaping time of 250 ns. (orig.).

  16. Plasma-filled diode experiments on PBFA-II

    International Nuclear Information System (INIS)

    Renk, T.J.; Rochau, G.E.; McDaniel, D.H.; Moore, W.B.; Zuchowski, N.; Padilla, R.

    1987-01-01

    The PBFA-II accelerator is designed to use a Plasma Opening Switch (POS) for pulse shaping and voltage multiplication using inductive storage. The vacuum section of the machine consists of a set of short magnetically insulated transmission lines (MITLs) that both act as a voltage adder for series stacking of the pulses out of the 72 parallel plate water lines, and as a 100 nH (total) storage inductor upstream of a biconically shaped POS region. There are two POS plasma injection areas, located above and below an equatorial load, which has consisted of either a short circuit, a blade (electron beam) diode, or an Applied B magnetically insulated ion diode. The POS is designed to conduct up to 6 MA, and open into a 5 ohm diode load in 10 ns or less. Under these conditions, the voltage at the load is predicted to exceed 24 MV. Initial POS experiments using these loads have produced 1) opening times of typically 20 ns or longer, 2) poor current transfer efficiency (less than 50%) when load impedances averaged 2 ohms or more, and 3) differential switch opening in azimuthal segments of the power feed, thought to be caused by poor plasma uniformity across the flashboard plasma source. One possible explanation for 2) is that efficient transfer out of the POS requires that the current carried to the load be magnetically insulated, or else considerable energy will be deposited in the feed region between the POS and load. This had indeed been observed. The problem is further exacerbated by the longer current turn-on times that occur when an ion diode is used as the load

  17. Extraction magnetically insulated diode studies on Gamble II

    International Nuclear Information System (INIS)

    Neri, J.M.; Boller, J.R.; Ottinger, P.F.; Stephanakis, S.J.; Greenly, J.

    1993-01-01

    An extraction Magnetically Insulated Diode (MID) with anode and cathode magnetic field coils has been tested on the NRL Gamble II accelerator. The purpose of the experiments is to develop an annular, intense ion beam source for testing ion beam transport physics related to light ion inertial confinement fusion. Initial experiments have been performed with surface flashover ion sources. The experimental challenge has been to obtain a tuning of the 4 magnetic field coils that results in a minimum turn-on time of the ion source and acceptable coupling to the accelerator. Results from several different geometries of magnetic field will be presented. The principal diode diagnostics are the total diode current, net ion current, and corrected diode voltage. Calculations of the magnetic field strength and geometry are performed with the ATHETA code. An active anode ion source is also under development. The initial portion of the accelerator pulse is diverted with a plasma opening switch (POS) and passed through a thin foil that will become the ion source. The foil is swiftly heated by the current pulse and gas is desorbed or diffused from the foil into the anode-cathode gap. The gas is then broken down by the current pulse, forming a dense plasma source on the anode surface. Two different foils are being used. A thin aluminum foil will work with desorbed gases, and provide a beam that is predominately protons. A hydrogen loaded titanium foil, with a paladium overcoating, will use diffused hydrogen, and produce a high purity proton beam. The net result of the POS and active anode plasma source should be much faster ion turn-on time, and better coupling of the ion source to the accelerator. Preliminary results with the active anode sources will be presented

  18. A new approach for multicriticality in directed and diode percolation

    International Nuclear Information System (INIS)

    Tsallis, C.; Boston Univ., MA; Redner, S.

    1983-01-01

    A new and very simple model for treating directed and more general diode percolation problems is presented, by allowing neighboring sites to be joined by up to two independent bonds of opposite orientations. A generalized 'break-collapse' method is developed to calculate renormalization group recursion relations. On the square lattice, a very symmetric phase diagram is obtained which displays multicritical percolation phenomena, and a variety of interesting conductivity transitions are predicted. (Author) [pt

  19. Chirp of monolithic colliding pulse mode-locked diode lasers

    DEFF Research Database (Denmark)

    Hofmann, M.; Bischoff, S.; Franck, Thorkild

    1997-01-01

    Spectrally resolved streak camera measurements of picosecond pulses emitted by hybridly colliding pulse mode-locked (CPM) laser diodes are presented in this letter. Depending on the modulation frequency both blue-chirped (upchirped) and red-chirped (downchirped) pulses can be observed. The two...... different regimes and the transition between them are characterized experimentally and the behavior is explained on the basis of our model for the CPM laser dynamics. (C) 1997 American Institute of Physics....

  20. Voltage Balancing Control of Diode-Clamped Multilevel Inverter

    Directory of Open Access Journals (Sweden)

    ŞCHIOP Adrian

    2013-10-01

    Full Text Available In this paper is developed a control scheme for mono-phase diode clamped inverter to achieve balancing voltages on inverter capacitors. First, it develops a control scheme without taking into account the need to balance voltage on two capacitors. It examines the effects on the output voltage inverter, and then it realizes two control schemes that will balance the voltages. The simulations of control schemes were performed in OrCAD Pspice.

  1. Rectification of electronic heat current by a hybrid thermal diode.

    Science.gov (United States)

    Martínez-Pérez, Maria José; Fornieri, Antonio; Giazotto, Francesco

    2015-04-01

    Thermal diodes--devices that allow heat to flow preferentially in one direction--are one of the key tools for the implementation of solid-state thermal circuits. These would find application in many fields of nanoscience, including cooling, energy harvesting, thermal isolation, radiation detection and quantum information, or in emerging fields such as phononics and coherent caloritronics. However, both in terms of phononic and electronic heat conduction (the latter being the focus of this work), their experimental realization remains very challenging. A highly efficient thermal diode should provide a difference of at least one order of magnitude between the heat current transmitted in the forward temperature (T) bias configuration (Jfw) and that generated with T-bias reversal (Jrev), leading to ℛ = Jfw/Jrev ≫ 1 or ≪ 1. So far, ℛ ≈ 1.07-1.4 has been reported in phononic devices, and ℛ ≈ 1.1 has been obtained with a quantum-dot electronic thermal rectifier at cryogenic temperatures. Here, we show that unprecedentedly high ratios of ℛ ≈ 140 can be achieved in a hybrid device combining normal metals tunnel-coupled to superconductors. Our approach provides a high-performance realization of a thermal diode for electronic heat current that could be successfully implemented in true low-temperature solid-state thermal circuits.

  2. Hybrid Light-Emitting Diode Enhanced With Emissive Nanocrystals

    DEFF Research Database (Denmark)

    Kopylov, Oleksii

    This thesis investigates a new type of white light emitting hybrid diode, composed of a light emitting GaN/InGaN LED and a layer of semiconductor nanocrystals for color conversion. Unlike standard white LEDs, the device is configured to achieve high color conversion efficiency via non-radiative e......This thesis investigates a new type of white light emitting hybrid diode, composed of a light emitting GaN/InGaN LED and a layer of semiconductor nanocrystals for color conversion. Unlike standard white LEDs, the device is configured to achieve high color conversion efficiency via non...... of the hybrid diode fabrication including process techniques for GaN LED and incorporation of the nanocrystals are presented with the emphasis on the differences with standard LED processing. Results and analysis of optical and electrical characterization including photoluminescence (PL), micro-PL, time......-resolved PL and electroluminescence (EL) together with current-voltage characteristics are presented to evaluate the device performance. A clear evidence of non-radiative energy transfer was seen in the carrier dynamics of both the LED and the nanocrystals when the quantum well – nanocrystals separation...

  3. Diode laser-pumped Ho:YLF laser

    International Nuclear Information System (INIS)

    Hemmati, H.

    1987-01-01

    The author reports laser action in Ho:YLF at 2.06 μm following optical pumping with a cw diode laser array. Diode laser-pumped Nd-YAG and Ho:YAG have been reported recently. Lasers with a wavelength of 2 μm have medical and optical communication applications. The diode laser light is focused with a 60-mm focal length lens onto the YLF crystal. A high-reflectivity mirror with 100-mm radius of curvature was used as the output coupler. The lasing threshold was at 5 mWof incident power. This is higher than expected considering that a high reflector was used as the output coupler. However, a more uniform cooling of the crystal is expected to lower the lasing threshold. With 100 mW of pump power coupled into the crystal, --20 mW of 2-μm radiation was observed from this unoptimized setup. The 2-μm laser output is highly sensitive to output coupler alignment, YLF crystal temperature, and pump laser wavelength. The 20% optical conversion efficiency achieved in his preliminary measurements is expected to be improved by better crystal cooling, proper matching of laser wavelength to crystal absorption, variations in the concentration of Ho and sensitizers and use of a proper output coupler. A study of the parameters mentioned above and the effect of crystal temperature on the laser output is under way

  4. Cultured Human Fibroblast Biostimulation Using a 940 nm Diode Laser

    Science.gov (United States)

    Illescas-Montes, Rebeca; Melguizo-Rodríguez, Lucía; Manzano-Moreno, Francisco Javier; García-Martínez, Olga; Ruiz, Concepción

    2017-01-01

    Background: Fibroblasts are the main cells involved in regeneration during wound healing. The objective was to determine the effect of 940 nm diode laser on cultured human fibroblasts using different irradiation regimens. Methods: The CCD-1064Sk human epithelial fibroblast cell line was treated with a 940 nm diode laser at different energy doses (power: 0.2–1 W and energy density: 1–7 J/cm2) using different transmission modes (continuous or pulsed). The effect on cell growth at 24 and 72 h post-treatment was examined by measuring the proliferative capacity, the impact on the cell cycle, and the effect on cell differentiation. Results: fibroblast proliferative capacity was increased at 24 and 72 h post-treatment as a function of the energy dose. The greatest increase was observed with a power of 0.2 or 0.5 W and energy density between 1 and 4 J/cm2; no difference was observed between continuous and pulsed modes. There were no significant differences in cell cycle between treated groups and controls. α-actin expression was increased by treatment, indicating enhanced cell differentiation. Conclusion: The 940 nm diode laser has biostimulating effects on fibroblasts, stimulating proliferative capacity and cell differentiation without altering the cell cycle. Further researches are necessary to explore its potential clinical usefulness in wound healing. PMID:28773152

  5. Perovskite Materials for Light-Emitting Diodes and Lasers.

    Science.gov (United States)

    Veldhuis, Sjoerd A; Boix, Pablo P; Yantara, Natalia; Li, Mingjie; Sum, Tze Chien; Mathews, Nripan; Mhaisalkar, Subodh G

    2016-08-01

    Organic-inorganic hybrid perovskites have cemented their position as an exceptional class of optoelectronic materials thanks to record photovoltaic efficiencies of 22.1%, as well as promising demonstrations of light-emitting diodes, lasers, and light-emitting transistors. Perovskite materials with photoluminescence quantum yields close to 100% and perovskite light-emitting diodes with external quantum efficiencies of 8% and current efficiencies of 43 cd A(-1) have been achieved. Although perovskite light-emitting devices are yet to become industrially relevant, in merely two years these devices have achieved the brightness and efficiencies that organic light-emitting diodes accomplished in two decades. Further advances will rely decisively on the multitude of compositional, structural variants that enable the formation of lower-dimensionality layered and three-dimensional perovskites, nanostructures, charge-transport materials, and device processing with architectural innovations. Here, the rapid advancements in perovskite light-emitting devices and lasers are reviewed. The key challenges in materials development, device fabrication, operational stability are addressed, and an outlook is presented that will address market viability of perovskite light-emitting devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Responses of diode detectors to radiation beams from teletherapy machines

    International Nuclear Information System (INIS)

    Malinda, Lora; Nasukha

    2003-01-01

    Responses of diode detectors to radiation beams from teletherapy machines. It has been carried out responses to two sets of diode detector by using the beams of teletherapy Co-60 and medical linear accelerator. Each set of consist of 8 diode detectors was irradiated by using gamma beams from teletherapy Co-60 machines and 6 MV and 10 MV foron beams from medical linear accelerator and 6.9.12.16. and 20 MeV electron beams from medical linear accelerator. The detectors were positioned on the phantom circularly and radially and electronic equilibrium condition for all type and energy beams. It was found that every detectors had own individual response and it is not to be uniformity, since the fluctuation in between 16.6 % to 30.9 %. All detectors responses are linear to gamma and foron beams, and also for energy above 6 MeV for electron beams. Nonlinearity response occurs for 6 MeV electron beam, it is probably from the assumption of electronic equilibrium

  7. Light Converting Inorganic Phosphors for White Light-Emitting Diodes

    Directory of Open Access Journals (Sweden)

    Chiao-Wen Yeh

    2010-03-01

    Full Text Available White light-emitting diodes (WLEDs have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or near-ultraviolet (nUV LEDs and photoluminescence phosphors. These solid-state LED lamps, rather than organic light emitting diode (OLED or polymer light-emitting diode (PLED, have a number of advantages over conventional incandescent bulbs and halogen lamps, such as high efficiency to convert electrical energy into light, reliability and long operating lifetime. To meet with the further requirement of high color rendering index, warm light with low color temperature, high thermal stability and higher energy efficiency for WLEDs, new phosphors that can absorb excitation energy from blue or nUV LEDs and generate visible emissions efficiently are desired. The criteria of choosing the best phosphors, for blue (450-480 nm and nUV (380-400 nm LEDs, strongly depends on the absorption and emission of the phosphors. Moreover, the balance of light between the emission from blue-nUV LEDs and the emissions from phosphors (such as yellow from Y3Al5O12:Ce3+ is important to obtain white light with proper color rendering index and color temperature. Here, we will review the status of phosphors for LEDs and prospect the future development.

  8. Light Converting Inorganic Phosphors for White Light-Emitting Diodes

    Science.gov (United States)

    Chen, Lei; Lin, Chun-Che; Yeh, Chiao-Wen; Liu, Ru-Shi

    2010-01-01

    White light-emitting diodes (WLEDs) have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or near-ultraviolet (nUV) LEDs) and photoluminescence phosphors. These solid-state LED lamps, rather than organic light emitting diode (OLED) or polymer light-emitting diode (PLED), have a number of advantages over conventional incandescent bulbs and halogen lamps, such as high efficiency to convert electrical energy into light, reliability and long operating lifetime. To meet with the further requirement of high color rendering index, warm light with low color temperature, high thermal stability and higher energy efficiency for WLEDs, new phosphors that can absorb excitation energy from blue or nUV LEDs and generate visible emissions efficiently are desired. The criteria of choosing the best phosphors, for blue (450−480 nm) and nUV (380−400 nm) LEDs, strongly depends on the absorption and emission of the phosphors. Moreover, the balance of light between the emission from blue-nUV LEDs and the emissions from phosphors (such as yellow from Y3Al5O12:Ce3+) is important to obtain white light with proper color rendering index and color temperature. Here, we will review the status of phosphors for LEDs and prospect the future development.

  9. Cultured Human Fibroblast Biostimulation Using a 940 nm Diode Laser

    Directory of Open Access Journals (Sweden)

    Rebeca Illescas-Montes

    2017-07-01

    Full Text Available Background: Fibroblasts are the main cells involved in regeneration during wound healing. The objective was to determine the effect of 940 nm diode laser on cultured human fibroblasts using different irradiation regimens. Methods: The CCD-1064Sk human epithelial fibroblast cell line was treated with a 940 nm diode laser at different energy doses (power: 0.2–1 W and energy density: 1–7 J/cm2 using different transmission modes (continuous or pulsed. The effect on cell growth at 24 and 72 h post-treatment was examined by measuring the proliferative capacity, the impact on the cell cycle, and the effect on cell differentiation. Results: fibroblast proliferative capacity was increased at 24 and 72 h post-treatment as a function of the energy dose. The greatest increase was observed with a power of 0.2 or 0.5 W and energy density between 1 and 4 J/cm2; no difference was observed between continuous and pulsed modes. There were no significant differences in cell cycle between treated groups and controls. α-actin expression was increased by treatment, indicating enhanced cell differentiation. Conclusion: The 940 nm diode laser has biostimulating effects on fibroblasts, stimulating proliferative capacity and cell differentiation without altering the cell cycle. Further researches are necessary to explore its potential clinical usefulness in wound healing.

  10. Process for preparing schottky diode contacts with predetermined barrier heights

    Science.gov (United States)

    Chang, Y. Austin; Jan, Chia-Hong; Chen, Chia-Ping

    1996-01-01

    A process is provided for producing a Schottky diode having a preselected barrier height .phi..sub.Bn. The substrate is preferably n-GaAs, the metallic contact is derived from a starting alloy of the Formula [.SIGMA.M.sub..delta. ](Al.sub.x Ga.sub.1-x) wherein: .SIGMA.M is a moiety which consists of at least one M, and when more than one M is present, each M is different, M is a Group VIII metal selected from the group consisting of nickel, cobalt, ruthenium, rhodium, indium and platinum, .delta. is a stoichiometric coefficient whose total value in any given .SIGMA.M moiety is 1, and x is a positive number between 0 and 1 (that is, x ranges from greater than 0 to less than 1). Also, the starting alloy is capable of forming with the substrate a two phase equilibrium reciprocal system of the binary alloy mixture [.SIGMA.M.sub..delta. ]Ga-[.SIGMA.M.sub..delta. ]Al-AlAs-GaAs. When members of an alloy subclass within this Formula are each preliminarily correlated with the barrier height .phi..sub.Bn of a contact producable therewith, then Schottky diodes of predetermined barrier heights are producable by sputtering and annealing. Further provided are the product Schottky diodes that are produced according to this process.

  11. Countercurrent in high-current microsecond diodes with magnetic insulation

    International Nuclear Information System (INIS)

    Bugaev, S.P.; Kim, A.A.; Koshelev, V.I.

    1979-01-01

    In order to increase the efficiency of the generation of tube electron beams in diodes and the efficiency of the electron beam current pulse duration studied is the formation of the electron counter current in microsecond diodes with magnetic insulation in dependence on the various geometry of the cathode joint. The experiments have been carried out at the accelerator with the following parameters: diode voltage from 400 to 600 kV, the front and duration of the pulse 75 ns and 1-2 μs respectively, beam current from 4 to 17 kA, magnetic field of 18 kGs. The current in the drift tube and the total current of the electron gun have been measured. Distributing resistance current of vacuum insulator has been controlled. Conclusions have been made, that, in the case when the diameters of cathode and cathode holder are equal, the electron current is being produced from the reverse side of cathode plasma, which expands across the magnetic field with the rate of (4-5)x10 5 sm/cs. The counter current value has constituted 15% of the total current at the use of reflector with the geometry repeating the shape of the magnetic field force lines, corresponding to the cathode radius. The counter current has not been present at the use of the flat reflector

  12. Endoscopic diode laser therapy for chronic radiation proctitis.

    Science.gov (United States)

    Polese, Lino; Marini, Lucia; Rizzato, Roberto; Picardi, Edgardo; Merigliano, Stefano

    2018-01-01

    The purpose of this study is to determine the effectiveness of endoscopic diode laser therapy in patients presenting rectal bleeding due to chronic radiation proctitis (CRP). A retrospective analysis of CRP patients who underwent diode laser therapy in a single institution between 2010 and 2016 was carried out. The patients were treated by non-contact fibers without sedation in an outpatient setting. Fourteen patients (median age 77, range 73-87 years) diagnosed with CRP who had undergone high-dose radiotherapy for prostatic cancer and who presented with rectal bleeding were included. Six required blood transfusions. Antiplatelet (three patients) and anticoagulant (two patients) therapy was not suspended during the treatments. The patients underwent a median of two sessions; overall, a mean of 1684 J of laser energy per session was used. Bleeding was resolved in 10/14 (71%) patients, and other two patients showed improvement (93%). Only one patient, who did not complete the treatment, required blood transfusions after laser therapy; no complications were noted during or after the procedures. Study findings demonstrated that endoscopic non-contact diode laser treatment is safe and effective in CRP patients, even in those receiving antiplatelet and/or anticoagulant therapy.

  13. Ion channelling analysis of pre-amorphised silicon diodes using a nuclear microprobe

    International Nuclear Information System (INIS)

    Thornton, J.; Paus, K.C.

    1988-01-01

    Aligned and random ion channelling analysis was performed on p + n diode structures in silicon, with the Surrey nuclear microprobe. Three different types of diode were investigated, each pre-amorphised by a different ion (Si + , Ge + or Sn + ) before the p + region was formed by BF 2 + implantation. The ion channelling measurements are presented and compared with previously published electrical measurements on these diodes. Relatively large residual disorder and junction leakage currents were found for the Si + pre-amorphised diodes; however, all the diodes were leaky. The results are consistent with dislocation loops within the depletion regions of the diodes causing both the residual disorder and the large leakage currents. Cross-sectional transmission electron microscopy studies support this model. (author)

  14. Extremely high-brightness kW-class fiber coupled diode lasers with wavelength stabilization

    Science.gov (United States)

    Huang, Robin K.; Chann, Bien; Glenn, John D.

    2011-06-01

    TeraDiode has produced ultra-high brightness fiber-coupled direct diode lasers. A fiber-coupled direct diode laser with a power level of 1,040 W from a 200 μm core diameter, 0.18 numerical aperture (NA) output fiber at a single center wavelength was demonstrated. This was achieved with a novel beam combining and shaping technique using COTS diode lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 18 mm-mrad and is the lowest BPP kW-class direct diode laser yet reported. The laser has been used to demonstrate laser cutting and welding of steel sheet metal up to 6.65 mm thick. Higher brightness fiber-coupled diode lasers, including a module with 418 W of power coupled to a 100 μm, 0.15 NA fiber, have also been demonstrated.

  15. Determination of reference data of REB diodes by using a numerical method for different applications

    International Nuclear Information System (INIS)

    Sinman, S.; Sinman, A.

    1982-01-01

    In this study, some reference data of a REB diode are presented functionally. These given characteristics are consisted of the computational results. Generally the numerical scheme depends upon the essential parameters of the charged transmission line and Child-Langmuir's diode model. By this system, further the correlation functions, some other definite functions such as the voltage of transmission line Vsub(L)(t), the diode voltage Vsub(d)(t), the diode current Isub(d)(t), the diode impedance Rsub(d)(t), the diode input power Wsub(d)(t), the dissipated energy Usub(d)(t), the efficiency phi, the beam density nsub(b)(t), the relativistic beam energy Usub(b)(t), and the intrinsic impedance Zsub(int)(t) have also been investigated. (author)

  16. Investigation on a radiation tolerant betavoltaic battery based on Schottky barrier diode

    International Nuclear Information System (INIS)

    Liu Yebing; Hu Rui; Yang Yuqing; Wang Guanquan; Luo Shunzhong; Liu Ning

    2012-01-01

    An Au–Si Schottky barrier diode was studied as the energy conversion device of betavoltaic batteries. Its electrical performance under radiation of Ni-63 and H-3 sources and radiation degradation under Am-241 were investigated and compared with those of the p–n junction. The results show that the Schottky diode had a higher I sc and harder radiation tolerance but lower V oc than the p–n junction. The results indicated that the Schottky diode can be a promising candidate for energy conversion of betavoltaic batteries. - Highlights: ► The Schottky diode was used as the converter of the betavoltaic battery. ► The radiation damage of converter was accelerated by using alpha particles. ► The Schottky diode has higher radiation resistance than that of the p–n junction. ► The Schottky diode could still be a promising converter of the betavoltaic battery.

  17. Effect of inductance between middle and outer cylinders on diode voltage of pulse forming line

    International Nuclear Information System (INIS)

    Liu Jinliang; Wang Xinxin

    2008-01-01

    Based on the experimental device of the water spiral pulse forming line(PFL) type electron beam accelerator, the effect of inductance between the middle and outer cylinders of PFL on diode voltage is theoretically and experimentally studied in this paper. The formulae are introduced, with which the effect of inductance on diode voltage is calculated. In addition, the diode voltage waveform is simulated through the Pspice software. The theoretical and simulated results agree well with the experimental results, which show that large inductance between middle and outer cylinders can shorten the waveform flat part of diode voltage, increase waveform rise time and reduce the diode peak voltage. When the inductance is smaller than 200 nH, a nearly square voltage waveform can be obtained in field-emission diode. (authors)

  18. Compact modeling of SiC Schottky barrier diode and its extension to junction barrier Schottky diode

    Science.gov (United States)

    Navarro, Dondee; Herrera, Fernando; Zenitani, Hiroshi; Miura-Mattausch, Mitiko; Yorino, Naoto; Jürgen Mattausch, Hans; Takusagawa, Mamoru; Kobayashi, Jun; Hara, Masafumi

    2018-04-01

    A compact model applicable for both Schottky barrier diode (SBD) and junction barrier Schottky diode (JBS) structures is developed. The SBD model considers the current due to thermionic emission in the metal/semiconductor junction together with the resistance of the lightly doped drift layer. Extension of the SBD model to JBS is accomplished by modeling the distributed resistance induced by the p+ implant developed for minimizing the leakage current at reverse bias. Only the geometrical features of the p+ implant are necessary to model the distributed resistance. Reproduction of 4H-SiC SBD and JBS current-voltage characteristics with the developed compact model are validated against two-dimensional (2D) device-simulation results as well as measurements at different temperatures.

  19. Ion production and bipolar fluxes in a high-current plasma-filled diode

    International Nuclear Information System (INIS)

    Ivanenkov, G.V.

    1982-01-01

    The model and the evolution of behaviour of binary layers (BL) in expanding plasma of high current plasma-filled diode are described. The model estimates ion current and the laws of plasma expansion at the stage of BL intensive growth. The density range (10 12 -10 15 cm -3 ) is determined in which diode impedance growth takes place in connection with BL appearance. The density of ion current at the outlet of diode is 10 A/cm 2

  20. Development of a high and low impedance diode testing facility at AWE Aldermaston

    International Nuclear Information System (INIS)

    Sinclair, M.; Aedy, Ch.; Cooper, G.

    2005-01-01

    To meet the future resolution targets for radiography of hydrodynamic experiments is creating a dedicated Diode Research Facility. To perform low impedance diode research, the X-ray simulator Eros has been acquired. To drive the high impedance diodes the EMU machine will be co-located with Eros. The co-located of machines will facilitate the sharing of plasma and X-ray diagnostics [ru

  1. Non-laminar flow model for the impedance of a rod-pinch diode

    International Nuclear Information System (INIS)

    Ottinger, Paul F.; Schumer, Joseph W.; Strasburg, Sean D.; Swanekamp, Stephen B.; Oliver, Bryan V.

    2002-01-01

    A previous laminar flow model for the rod-pinch diode is extended to include a transverse pressure term to study the effects of non-laminar flow. The non-laminar nature of the flow has a significant impact on the diode impedance. Results show that the introduction of the transverse pressure decreases the diode impedance predicted by the model bringing it into better agreement with experimental data

  2. Shot reproducibility of the self-magnetic-pinch diode at 4.5 MV

    OpenAIRE

    Nichelle Bennett; M. Dale Crain; Darryl W. Droemer; Raymond E. Gignac; Greg Lare; Isidro Molina; Robert Obregon; Chase C. Smith; Frank L. Wilkins; Dale R. Welch; Steve Cordova; Manuel L. Gallegos; Mark D. Johnston; Mark L. Kiefer; Joshua J. Leckbee

    2014-01-01

    In experiments conducted at Sandia National Laboratories’ RITS-6 accelerator, the self-magnetic-pinch diode exhibits significant shot-to-shot variability. Specifically, for identical hardware operated at the same voltage, some shots exhibit a catastrophic drop in diode impedance. A study is underway to identify sources of shot-to-shot variations which correlate with diode impedance collapse. The scope of this report is limited to data collected at 4.5-MV peak voltage and sources of variabilit...

  3. Low-threshold amplitude discriminator circuit with tunnel diode and two transistors in differential connection

    International Nuclear Information System (INIS)

    Ryba, J.; Volny, J.

    1973-01-01

    The connection is designed of a low-threshold amplitude discriminator and a tunnel diode with two transistors in differential connection. The discriminator is by its simple connection, its low consumption and high temperature stability suitable especially for portable radiation detectors. The tunnel diode is connected by one pole to a collector clamp and by the other to the supply voltage. A suitable resistor is connected in parallel with the tunnel diode to meet demands for higher sensitivity. (Z.S.)

  4. Investigation of thermometrical characteristics of p+–n-GaP diodes

    Directory of Open Access Journals (Sweden)

    Sypko N. I.

    2008-12-01

    Full Text Available The method of reception of p+–n-diode epitaxial structures of GaP from liquid phase is developed. In the temperature range of 80—520 K thermometric and current-voltage characteristics of test models of diode temperature sensors are measured and their basic technical parameters are determined. Perspectivity of developed GaP-diodes application as sensitive elements of high-temperature sensor is shown.

  5. Electrical and optical response of a laser diode to transient ionizing radiation

    International Nuclear Information System (INIS)

    Baggio, J.; Brisset, C.; Sommer, J.L.; D'hose, C.; Lalande, P.; Leray, J.L.; Musseau, O.

    1996-01-01

    The authors have studied transient irradiation effects on the optical and electrical responses of a laser diode. The influence of dose rate, ranging from 10 9 to 10 12 rad(Si)/s, has been investigated through a complete experimental study. Dose rate vulnerability of the laser diode has been observed. Electrical and optical transient responses are determined by the dose rate, the diode structure, and its operating point

  6. Femtosecond Nonlinearities in Indium Gallium Arsenic Phosphide Diode Lasers

    Science.gov (United States)

    Hall, Katherine Lavin

    Semiconductor optical amplifiers are receiving increasing attention for possible applications to broadband optical communication and switching systems. In this thesis we report the results of an extensive experimental study of the ultrafast gain and refractive index nonlinearities in 1.5 μm InGaAsP laser diode amplifiers. The temporal resolution afforded by the femtosecond optical pulses used in these experiments allows us to study carrier interactions with other carriers as well as carrier interactions with the lattice. The 100-200 fs optical pulses used in the pump -probe experiments are generated by an Additive Pulse Modelocked color center laser. The measured group velocity dispersion in the diodes ranged from -0.6 to -0.95 mu m^{-1 }. Differences in the group velocity for TE - and TM-polarized pulses suggested that cross-polarized pump-probe pulses walk off from each other in the diode. This walk-off can diminish the time resolution of some experiments. A novel heterodyne pump-probe technique was developed to distinguish collinear, copolarized, pump and probe pulses that were nominally at the same wavelength. Comparing cross-polarized and copolarized pump-probe results yielded new information about the physical mechanisms responsible for nonlinear gain in the diodes. We observed a gain compression across the entire bandwidth of the diode, associated with carrier heating. The hot carrier distribution cooled back to the lattice temperature with a 0.6 to 1.0 ps time constant, depending on the device structure. In addition, we observed a 0.1 to 0.25 ps delay in onset of carrier heating. Large gain compression due to two photon absorption was also observed. A small portion of the nonlinear gain is attributed to spectral hole burning. Pulsewidth-dependent output saturation energies were explained by a rate equation model that included the effect of carrier heating. Measurements of pump-induced probe phase changes revealed index nonlinearities due to delayed carrier

  7. A mathematical modeling framework to evaluate the performance of single diode and double diode based SPV systems

    Directory of Open Access Journals (Sweden)

    Sangram Bana

    2016-11-01

    Full Text Available In order to predict the performance of a PV system, a reliable and accurate simulation design of PV systems before being installed is a necessity. The present study concerns the development of single and double diode model of solar PV system and ensures the best suited model under specific environmental condition for accurate performance prediction. The information provided in the manufacturers’ data sheet is not sufficient for developing a Simulink based single and double diode models of PV module. These parameters are crucial to predict accurate performance of a PV module. These parameters of the proposed solar PV models have been calculated using an efficient iterative technique. This paper compares the simulation results of both the models with manufacturer’s data sheet to investigate the accuracy and validity. A MATLAB/Simulink based comparative performance analysis of these models under inconsistent atmospheric conditions and the effect of variations in model parameters has been carried out. Despite the simplicity, these models are highly sensitive and respond to a slight variation in temperature and insolation. It is observed that double diode PV model is more accurate under low intensity insolation or shading condition. The performance evaluation of the models under present study will be helpful to understand the I-V curves, which will enable us in predicting the solar PV system power production under variable input conditions.

  8. Semiconductor Laser Diode Pumps for Inertial Fusion Energy Lasers

    International Nuclear Information System (INIS)

    Deri, R.J.

    2011-01-01

    Solid-state lasers have been demonstrated as attractive drivers for inertial confinement fusion on the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) and at the Omega Facility at the Laboratory for Laser Energetics (LLE) in Rochester, NY. For power plant applications, these lasers must be pumped by semiconductor diode lasers to achieve the required laser system efficiency, repetition rate, and lifetime. Inertial fusion energy (IFE) power plants will require approximately 40-to-80 GW of peak pump power, and must operate efficiently and with high system availability for decades. These considerations lead to requirements on the efficiency, price, and production capacity of the semiconductor pump sources. This document provides a brief summary of these requirements, and how they can be met by a natural evolution of the current semiconductor laser industry. The detailed technical requirements described in this document flow down from a laser ampl9ifier design described elsewhere. In brief, laser amplifiers comprising multiple Nd:glass gain slabs are face-pumped by two planar diode arrays, each delivering 30 to 40 MW of peak power at 872 nm during a ∼ 200 (micro)s quasi-CW (QCW) pulse with a repetition rate in the range of 10 to 20 Hz. The baseline design of the diode array employs a 2D mosaic of submodules to facilitate manufacturing. As a baseline, they envision that each submodule is an array of vertically stacked, 1 cm wide, edge-emitting diode bars, an industry standard form factor. These stacks are mounted on a common backplane providing cooling and current drive. Stacks are conductively cooled to the backplane, to minimize both diode package cost and the number of fluid interconnects for improved reliability. While the baseline assessment in this document is based on edge-emitting devices, the amplifier design does not preclude future use of surface emitting diodes, which may offer appreciable future cost reductions and

  9. Enhanced Performance of Bipolar Cascade Light Emitting Diodes by Doping the Aluminum Oxide Apertures

    National Research Council Canada - National Science Library

    Siskaninetz, William

    2004-01-01

    Performance improvements in multiple-stage, single-cavity bipolar cascade light emitting diodes including reduced operating voltages, enhanced light generation, and reduced device heating are obtained...

  10. InGaAs/InP heteroepitaxial Schottky barrier diodes for terahertz applications

    Science.gov (United States)

    Bhapkar, Udayan V.; Li, Yongjun; Mattauch, Robert J.

    1992-01-01

    This paper explores the feasibility of planar, sub-harmonically pumped, anti-parallel InGaAs/InP heteroepitaxial Schottky diodes for terahertz applications. We present calculations of the (I-V) characteristics of such diodes using a numerical model that considers tunneling. We also present noise and conversion loss predictions of diode mixers operated at 500 GHz, and obtained from a multi-port mixer analysis, using the I-V characteristics predicted by our model. Our calculations indicate that InGaAs/InP heteroepitaxial Schottky barrier diodes are expected to have an I-V characteristic with an ideality factor comparable to that of GaAs Schottky diodes. However, the reverse saturation current of InGaAs/InP diodes is expected to be much greater than that of GaAs diodes. These predictions are confirmed by experiment. The mixer analyses predict that sub-harmonically pumped anti-parallel InGaAs/InP diode mixers are expected to offer a 2 dB greater conversion loss and a somewhat higher single sideband noise temperature than their GaAs counterparts. More importantly, the InGaAs/InP devices are predicted to require only one-tenth of the local oscillator power required by similar GaAs diodes.

  11. Theory and experiment on charging and discharging a capacitor through a reverse-biased diode

    Science.gov (United States)

    Roy, Arijit; Mallick, Abhishek; Adhikari, Aparna; Guin, Priyanka; Chatterjee, Dibyendu

    2018-06-01

    The beauty of a diode lies in its voltage-dependent nonlinear resistance. The voltage on a charging and discharging capacitor through a reverse-biased diode is calculated from basic equations and is found to be in good agreement with experimental measurements. Instead of the exponential dependence of charging and discharging voltages with time for a resistor-capacitor circuit, a linear time dependence is found when the resistor is replaced by a reverse-biased diode. Thus, well controlled positive and negative ramp voltages are obtained from the charging and discharging diode-capacitor circuits. This experiment can readily be performed in an introductory physics and electronics laboratory.

  12. Comparison of SHG Power Modulation by Wavelength Detuning of DFB- and DBR-Tapered Laser Diodes

    DEFF Research Database (Denmark)

    Christensen, Mathias; Hansen, Anders Kragh; Noordegraaf, Danny

    2016-01-01

    of the response of the second harmonic light to perturbations of the infrared laser diode and compare how the response differs for DFB- and DBR-Tapered laser diodes. We show that the visible light can be modulated from CW to kHz with modulation depths above 90% by wavelength detuning the laser diode.......Pulsed visible lasers are used for a number of applications such as laser displays and medical treatments. Generating this visible light by direct frequency doubling of high power diode lasers opens new possibilities on how the power modulation can be performed. We present an investigation...

  13. Fabrication study of GaAs mesa diodes for X-ray detection

    OpenAIRE

    Ng, J.S.; Meng, X.; Lees, J.E.; Barnett, A.; Tan, C.H.

    2014-01-01

    A study of leakage currents using GaAs mesa p-i-n diodes for X-ray photon counting is presented. Different wet chemical etching solution and etch depth were used in the fabrication of these mesa diodes. Low and uniform leakage currents were achieved when the diode fabrication used (i) a combination of main etching solution and finishing etching solution for the etching, and (ii) partially etched mesas. The diodes fabricated using these methods showed well-defined X-ray peaks when illuminated ...

  14. Testing of high current by-pass diodes for the LHC magnet quench protection

    International Nuclear Information System (INIS)

    Berland, V.; Hagedorn, D.; Rodriguez-Mateos, F.

    1996-01-01

    Within the framework of the Large Hadron Collider (LHC) R and D program, CERN is performing experiments to establish the current carrying capability of irradiated diodes at liquid Helium temperatures for the superconducting magnet protection. Even if the diodes are degraded by radiation dose and neutron fluence, they must be able to support the by-pass current during a magnet quench and the de-excitation of the superconducting magnet ring. During this discharge, the current in the diode reaches a maximum value up to 13 kA and decreased with an exponential time constant of 100 s. Two sets of 75 mm wafer diameter epitaxial diodes, one irradiated and one non-irradiated, were submitted to this experiment. The irradiated diodes have been exposed to radiation in the accelerator environment up to 20 kGy and then annealed at room temperature. After the radiation exposure the diodes had shown a degradation of forward voltage of 50% which reduced to about 14% after the thermal annealing. During the long duration high current tests, one of the diodes was destroyed and the other two irradiated diodes showed a different behavior compared with non-irradiated diodes

  15. Electron inertia effects for an electron fluid model by the applied-B ion diode

    Energy Technology Data Exchange (ETDEWEB)

    Gordeev, A V; Levchenko, S V [Kurchatov Institute, Moscow (Russian Federation). Nuclear Fusion Institute

    1997-12-31

    Numerical calculations within the framework of the one-dimensional vortex-like electron fluid model in applied-B ion diodes, taking account the electron inertia effects, are presented. The existence of the additional relation between the magnetic field and the electric potential offers an opportunity to reduce the ion diode problem to the system of the algebraic equations for the constants introduced. The ion current density in an ion diode is determined only by the magnetic flux cut out by the virtual cathode. As an illustration, the ion diode impedance for the KALIF device was calculated. (author). 2 figs., 6 refs.

  16. Non-Reciprocal Geometric Wave Diode by Engineering Asymmetric Shapes of Nonlinear Materials

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Jie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Li, Nianbei [Tongji Univ., Shanghai Shi (China)

    2014-02-18

    Unidirectional nonreciprocal transport is at the heart of many fundamental problems and applications in both science and technology. Here we study how to design the novel wave diode devices to realize the non-reciprocal wave propagations. Analytical results reveal that such non-reciprocal wave propagation can be purely induced by asymmetric geometry in nonlinear materials. The detailed numerical simulations are performed for a more realistic geometric wave diode model with typical asymmetric shape, where good non-reciprocal wave diode effect has been demonstrated. The results open a way for making wave diodes efficiently simply through shape engineering.

  17. Fabrication and Characterization of Schottky Diodes using Single Wall Carbon Nanotubes

    National Research Council Canada - National Science Library

    Luquette, Brandon E; Nichols, Barbara M

    2008-01-01

    .... Multiple cleanroom processing steps were used to make the diodes which included the deposition of marker layers, oxygen plasma etch for selective nanotube removal, and electron beam evaporation...

  18. Tunable high-power narrow-linewidth green external-cavity GaN diode laser

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2016-01-01

    A tunable high-power green external-cavity diode laser is demonstrated. Up to 290 mW output power and a 9.2 nm tuning is achieve. This constitutes the highest output power from a tunable green diode laser system.......A tunable high-power green external-cavity diode laser is demonstrated. Up to 290 mW output power and a 9.2 nm tuning is achieve. This constitutes the highest output power from a tunable green diode laser system....

  19. V-shaped resonators for addition of broad-area laser diode arrays

    Science.gov (United States)

    Liu, Bo; Liu, Yun; Braiman, Yehuda Y.

    2012-12-25

    A system and method for addition of broad-area semiconductor laser diode arrays are described. The system can include an array of laser diodes, a V-shaped external cavity, and grating systems to provide feedback for phase-locking of the laser diode array. A V-shaped mirror used to couple the laser diode emissions along two optical paths can be a V-shaped prism mirror, a V-shaped stepped mirror or include multiple V-shaped micro-mirrors. The V-shaped external cavity can be a ring cavity. The system can include an external injection laser to further improve coherence and phase-locking.

  20. In Vivo Diode Dosimetry for Imrt Treatments Generated by Pinnacle Treatment Planning System

    International Nuclear Information System (INIS)

    Alaei, Parham; Higgins, Patrick D.; Gerbi, Bruce J.

    2009-01-01

    Dose verification using diodes has been proposed and used for intensity modulated radiation therapy (IMRT) treatments. We have previously evaluated diode response for IMRT deliveries planned with the Eclipse/Helios treatment planning system. The Pinnacle treatment planning system generates plans that are delivered in a different fashion than Eclipse. Whereas the Eclipse-generated segments are delivered in organized progression from one side of each field to the other, Pinnacle-generated segments are delivered in a much more randomized fashion to different areas within the field. This makes diode measurements at a point more challenging because the diode may be exposed fully or partially to multiple small segments during one single field's treatment as opposed to being exposed to very few segments scanning across the diode during an Eclipse-generated delivery. We have evaluated in vivo dosimetry for Pinnacle-generated IMRT plans and characterized the response of the diode to various size segments on phantom. We present results of patient measurements on approximately 300 fields, which show that 76% of measurements agree to within 10% of the treatment-plan generated calculated doses. Of the other 24%, about 11% are within 15% of the calculated dose. Comparison of these with phantom measurements indicates that many of the discrepancies are due to diode positioning on patients and increased diode response at short source-to-surface distances (SSDs), with the remainder attributable to other factors such as segment size and partial irradiation of the diode

  1. Spectral perturbations from silicon diode detector encapsulation and shielding in photon fields.

    Science.gov (United States)

    Eklund, Karin; Ahnesjö, Anders

    2010-11-01

    Silicon diodes are widely used as detectors for relative dose measurements in radiotherapy. The common manufacturing practice is to encapsulate the diodes in plastic for protection and to facilitate mounting in scanning devices. Diodes intended for use in photon fields commonly also have a shield of a high atomic number material (usually tungsten) integrated into the encapsulation to selectively absorb low-energy photons to which silicon diodes would otherwise over-response. However, new response models based on cavity theories and spectra calculations have been proposed for direct correction of the readout from unshielded (e.g., "electron") diodes used in photon fields. This raises the question whether it is correct to assume that the spectrum in a water phantom at the location of the detector cavity is not perturbed by the detector encapsulation materials. The aim of this work is to investigate the spectral effects of typical encapsulations, including shielding, used for clinical diodes. The effects of detector encapsulation of an unshielded and a shielded commercial diode on the spectra at the detector cavity location are studied through Monte Carlo simulations with PENELOPE-2005. Variance reduction based on correlated sampling is applied to reduce the CPU time needed for the simulations. The use of correlated sampling is found to be efficient and to not introduce any significant bias to the results. Compared to reference spectra calculated in water, the encapsulation for an unshielded diode is demonstrated to not perturb the spectrum, while a tungsten shielded diode caused not only the desired decrease in low-energy scattered photons but also a large increase of the primary electron fluence. Measurements with a shielded diode in a 6 MV photon beam proved that the shielding does not completely remove the field-size dependence of the detector response caused by the over-response from low-energy photons. Response factors of a properly corrected unshielded diode

  2. Vortex Diode Analysis and Testing for Fluoride Salt-Cooled High-Temperature Reactors

    International Nuclear Information System (INIS)

    Yoder, Graydon L. Jr.; Elkassabgi, Yousri M.; De Leon, Gerardo I.; Fetterly, Caitlin N.; Ramos, Jorge A.; Cunningham, Richard Burns

    2012-01-01

    Fluidic diodes are presently being considered for use in several fluoride salt-cooled high-temperature reactor designs. A fluidic diode is a passive device that acts as a leaky check valve. These devices are installed in emergency heat removal systems that are designed to passively remove reactor decay heat using natural circulation. The direct reactor auxiliary cooling system (DRACS) uses DRACS salt-to-salt heat exchangers (DHXs) that operate in a path parallel to the core flow. Because of this geometry, under normal operating conditions some flow bypasses the core and flows through the DHX. A flow diode, operating in reverse direction, is-used to minimize this flow when the primary coolant pumps are in operation, while allowing forward flow through the DHX under natural circulation conditions. The DRACSs reject the core decay heat to the environment under loss-of-flow accident conditions and as such are a reactor safety feature. Fluidic diodes have not previously been used in an operating reactor system, and therefore their characteristics must be quantified to ensure successful operation. This report parametrically examines multiple design parameters of a vortex-type fluidic diode to determine the size of diode needed to reject a particular amount of decay heat. Additional calculations were performed to size a scaled diode that could be tested in the Oak Ridge National Laboratory Liquid Salt Flow Loop. These parametric studies have shown that a 152.4 mm diode could be used as a test article in that facility. A design for this diode is developed, and changes to the loop that will be necessary to test the diode are discussed. Initial testing of a scaled flow diode has been carried out in a water loop. The 150 mm diode design discussed above was modified to improve performance, and the final design tested was a 171.45 mm diameter vortex diode. The results of this testing indicate that diodicities of about 20 can be obtained for diodes of this size. Experimental

  3. Cryogenic Testing of High Current By-Pass Diode Stacks for the Protection of the Superconducting Magnets in the LHC

    Science.gov (United States)

    Gharib, A.; Hagedorn, D.; Della Corte, A.; Fiamozzi Zignani, C.; Turtu, S.; Brown, D.; Rout, C.

    2004-06-01

    For the protection of the LHC superconducting magnets, about 2100 specially developed by-pass diodes were manufactured by DYNEX SEMICONDUCTOR LTD (Lincoln, GB) and about 1300 of these diodes were mounted into diode stacks and submitted to tests at cryogenic temperatures. To date about 800 dipole diode stacks and about 250 quadrupole diode stacks for the protection of the superconducting lattice dipole and lattice quadrupole magnets have been assembled at OCEM (Bologna,Italy) and successfully tested in liquid helium at ENEA (Frascati, Italy). This report gives an overview of the test results obtained so far. After a short description of the test installations and test procedures, a statistical analysis is presented for test data during diode production as well as for the performance of the diode stacks during testing in liquid helium, including failure rates and degradation of the diodes.

  4. Barrier inhomogeneities limited current and 1/f noise transport in GaN based nanoscale Schottky barrier diodes

    Science.gov (United States)

    Kumar, Ashutosh; Heilmann, M.; Latzel, Michael; Kapoor, Raman; Sharma, Intu; Göbelt, M.; Christiansen, Silke H.; Kumar, Vikram; Singh, Rajendra

    2016-01-01

    The electrical behaviour of Schottky barrier diodes realized on vertically standing individual GaN nanorods and array of nanorods is investigated. The Schottky diodes on individual nanorod show highest barrier height in comparison with large area diodes on nanorods array and epitaxial film which is in contrast with previously published work. The discrepancy between the electrical behaviour of nanoscale Schottky diodes and large area diodes is explained using cathodoluminescence measurements, surface potential analysis using Kelvin probe force microscopy and 1ow frequency noise measurements. The noise measurements on large area diodes on nanorods array and epitaxial film suggest the presence of barrier inhomogeneities at the metal/semiconductor interface which deviate the noise spectra from Lorentzian to 1/f type. These barrier inhomogeneities in large area diodes resulted in reduced barrier height whereas due to the limited role of barrier inhomogeneities in individual nanorod based Schottky diode, a higher barrier height is obtained. PMID:27282258

  5. Gamma radiation processing dosimetry with commercial silicon diodes

    International Nuclear Information System (INIS)

    Ferreira, Danilo Cardenuto

    2009-01-01

    This work envisages the development of dosimeters based on Si diodes for gamma radiation dosimetry from 1 Gy up to 100 Gy. This dose range is frequently utilized in radiation processing of crystal modifications, polymers crosslinking and biological studies carried out in the Radiation Technology Center at IPEN-CNEN/SP. The dosimeter was constructed by a commercial SFH00206 (Siemens) Si diode, operating in a photovoltaic mode, whose electrical characteristics are suitable for this application. The current generated in the device by the Cobalt-60 gamma radiation from the Irradiators types I and II was registered with a digital electrometer and stored during the exposure time. In all measurements, the current signals of the diode registered as a function of the exposure time were very stable. Furthermore, the device photocurrent was linearly dependent on the dose rate within a range of 6.1x10 -2 Gy/min up to 1.9x10 2 Gy/min. The calibration curves of the dosimeters, e.g., the average charge registered as a function of the absorbed dose were obtained by the integration of the current signals as a function of the exposure time. The results showed a linear response of the dosimeter with a correlation coefficient better than 0.998 for total absorbed dose up to 120 Gy. Finally, due to the small experimental errors 5 % it was also possible to measure the transit dose due to the movement of the Cobalto- 60 radioactive sources in irradiation facilities used in this work. (author)

  6. Experimental transconjunctival diode laser retinal photocoagulation through silicone scleral exoplants.

    Science.gov (United States)

    Nanda, S K; Han, D P

    1995-07-01

    To study the feasibility of inducing a chorioretinal lesion under a previously placed scleral buckle by experimental transconjunctival diode laser photocoagulation. We performed transconjunctival diode laser photocoagulation in the peripheral retinas of seven pigmented rabbit eyes with a silicone exoplant (No. 42 band or No. 276 tire) and seven eyes without an exoplant. Each eye received burns with an intensity of grades 1 to 3 in different quadrants at varying power levels, with a 0.5-second duration and 650-micron spot size. Eyes were enucleated for histopathologic studies 1 day and 1 week after treatment. Although the irradiance emitted through the No. 42 band and the No. 276 tire was attenuated by 17% and 23%, respectively, the range of threshold powers needed to produce grades 1 to 3 burns was similar between eyes with and without a silicone exoplant. At 1 day, full-thickness coagulative necrosis was observed in all lesions, except that the ganglion cell layer and inner nuclear layer were preserved in two of four grade 1 burns and the ganglion cell layer was intact in one of six grade 2 burns. Inner scleral changes were noted acutely in three of five grade 3 lesions. At 1 week, burns of all intensity grades showed a full-thickness atrophic chorioretinal lesion with inner scleral changes. Experimental transconjunctival diode laser photocoagulation through hard silicone elements reproducibly created a chorioretinal lesion with histopathologic findings similar to those of lesions obtained without these elements. Although retinal photocoagulative effects were prominent, inner scleral abnormalities were also observed histologically.

  7. Research of long pulse high current diode radial insulation

    International Nuclear Information System (INIS)

    Tan Jie; Chang Anbi; Hu Kesong; Liu Qingxiang; Ma Qiaosheng; Liu Zhong

    2002-01-01

    A radial insulation structure which is used in long pulse high current diode is introduced. The theory of vacuum flashover and the idea of design are briefly introduced. In the research, cone-shaped insulator was used. The geometry structure parameters were optimized by simulating the static electrical field distribution. Experiment was done on a pulse power source with 200 ns pulse width. The maximum voltage 750 kV was obtained, and the average stand-off electrical field of insulator is about 50 kV/cm

  8. Temperature dependent charge transport in poly(3-hexylthiophene) diodes

    Science.gov (United States)

    Rahaman, Abdulla Bin; Sarkar, Atri; Banerjee, Debamalya

    2018-04-01

    In this work, we present charge transport properties of poly(3-hexylthiophene) (P3HT) diodes under dark conditions. Temperature dependent current-voltage (J-V) characteristics shows that charge transport represents a transition from ohomic to trap limited current. The forward current density obeys a power law J˜Vm, m>2 represents the space charge limited current region in presence of traps within the band gap. Frequency dependent conductivity has been studied in a temperature range 150K-473K. The dc conductivity values show Arrhenius like behavior and it gives conductivity activation energy 223 meV. Temperature dependent conductivity indicates a thermodynamic transition of our system.

  9. Modelling of optoelectronic circuits based on resonant tunneling diodes

    Science.gov (United States)

    Rei, João. F. M.; Foot, James A.; Rodrigues, Gil C.; Figueiredo, José M. L.

    2017-08-01

    Resonant tunneling diodes (RTDs) are the fastest pure electronic semiconductor devices at room temperature. When integrated with optoelectronic devices they can give rise to new devices with novel functionalities due to their highly nonlinear properties and electrical gain, with potential applications in future ultra-wide-band communication systems (see e.g. EU H2020 iBROW Project). The recent coverage on these devices led to the need to have appropriated simulation tools. In this work, we present RTD based optoelectronic circuits simulation packages to provide circuit signal level analysis such as transient and frequency responses. We will present and discuss the models, and evaluate the simulation packages.

  10. Development of X-ray diode with high performance

    International Nuclear Information System (INIS)

    Hou Lifei; Yang Gouhong; Liu Shenye; Wei Minxi; Yi Tao; Jiang Shao'en; Sun Kexu

    2011-01-01

    A new type of X-ray diode (XRD-II) with ultrafast response time was developed. XRD-II detector was improved on the basis of old XRD (XRD-I), and its performances were studied on the 8 ps laser facility. The results show that XRD-II has excellent high-Jantage tolerance (to 6 kV) and super-fast response time (rise time is about 40 ps, and full width at half maximum (FWHM) is about 80 ps when bias Jantage is 5 kV). The detector calibration was carried out on Beijing synchrotron radiation facility, which shows that the detector's sensitivity has not deteriorated. (authors)

  11. Resection of the Tooth Apex with Diode Laser

    Directory of Open Access Journals (Sweden)

    Uzunov Tz.

    2014-06-01

    Full Text Available An “in vitro” experimental study has been carried out on 70 extracted teeth. A laser resection of the root apex has been carried out with diode laser beam with a wavelength of - 810 ± 10 nm. Sequentially a radiation with increasing power has been applied, as follows: 1,3 W, 2W, 3W, 4W, 5W, 6W, 7W, in electro surgery mode. Successful resection of the tooth apex has been performed at: 3W; 4W; 5W; 6W and 7W power. It was established that when laser resected the tooth apex carbonizes.

  12. Diode laser excited optogalvanic spectroscopy of glow discharges

    International Nuclear Information System (INIS)

    Barshick, C.M.; Shaw, R.W.; Jennings, L.W.; Post-Zwicker, A.; Young, J.P.; Ramsey, J.M.

    1997-01-01

    The development of diode-laser-excited isotopically-selective optogalvanic spectroscopy (OGS) of uranium metal, oxide and fluoride in a glow discharge (GD) is presented. The technique is useful for determining 235 U/( 235 U+ 238 U) isotope ratios in these samples. The precision and accuracy of this determination is evaluated, and a study of experimental parameters pertaining to optimization of the measurement is discussed. Application of GD-OGS to other f-transition elements is also described. copyright 1997 American Institute of Physics

  13. Optimization of the particle pusher in a diode simulation code

    International Nuclear Information System (INIS)

    Theimer, M.M.; Quintenz, J.P.

    1979-09-01

    The particle pusher in Sandia's particle-in-cell diode simulation code has been rewritten to reduce the required run time of a typical simulation. The resulting new version of the code has been found to run up to three times as fast as the original with comparable accuracy. The cost of this optimization was an increase in storage requirements of about 15%. The new version has also been written to run efficiently on a CRAY-1 computing system. Steps taken to affect this reduced run time are described. Various test cases are detailed

  14. Detection of elemental mercury by multimode diode laser correlation spectroscopy.

    Science.gov (United States)

    Lou, Xiutao; Somesfalean, Gabriel; Svanberg, Sune; Zhang, Zhiguo; Wu, Shaohua

    2012-02-27

    We demonstrate a method for elemental mercury detection based on correlation spectroscopy employing UV laser radiation generated by sum-frequency mixing of two visible multimode diode lasers. Resonance matching of the multimode UV laser is achieved in a wide wavelength range and with good tolerance for various operating conditions. Large mode-hops provide an off-resonance baseline, eliminating interferences from other gas species with broadband absorption. A sensitivity of 1 μg/m3 is obtained for a 1-m path length and 30-s integration time. The performance of the system shows promise for mercury monitoring in industrial applications.

  15. Gas detection by correlation spectroscopy employing a multimode diode laser.

    Science.gov (United States)

    Lou, Xiutao; Somesfalean, Gabriel; Zhang, Zhiguo

    2008-05-01

    A gas sensor based on the gas-correlation technique has been developed using a multimode diode laser (MDL) in a dual-beam detection scheme. Measurement of CO(2) mixed with CO as an interfering gas is successfully demonstrated using a 1570 nm tunable MDL. Despite overlapping absorption spectra and occasional mode hops, the interfering signals can be effectively excluded by a statistical procedure including correlation analysis and outlier identification. The gas concentration is retrieved from several pair-correlated signals by a linear-regression scheme, yielding a reliable and accurate measurement. This demonstrates the utility of the unsophisticated MDLs as novel light sources for gas detection applications.

  16. Improved emission spectrum from quantum dot superluminescent light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Li, L.H.; Rossetti, M.; Fiore, A. [Institute of Photonics and Quantum Electronics, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland); Occhi, L.; Velez, C. [EXALOS AG, Technoparkstrasse 1, 8005 Zuerich (Switzerland)

    2006-12-15

    The size dispersion of InAs quantum dots (QD) was optimized to broaden the photoluminescence (PL) spectrum. A broad PL spectral width up to 96 nm is achieved from a single QD layer with InAs thickness smaller than 2.4 monolayers at a growth temperature of 510 C. QD Superluminescent light emitting diodes with an ultrawide (115 nm), smooth output spectrum are obtained by incorporating this QD layer into chirped stacked structures. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Simplified Chua's attractor via bridging a diode pair

    Directory of Open Access Journals (Sweden)

    Quan Xu

    2015-04-01

    Full Text Available In this paper, a simplified Chua's circuit is realised by bridging a diode pair between a passive LC (inductance and capacitance in parallel connection - LC oscillator and an active RC (resistance and capacitance in parallel connection - RC filter. The dynamical behaviours of the circuit are investigated by numerical simulations and verified by experimental measurements. It is found that the simplified Chua's circuit generates Chua's attractors similarly and demonstrates complex non-linear phenomena including coexisting bifurcation modes and coexisting attractors in particular.

  18. Spin injection in n-type resonant tunneling diodes.

    Science.gov (United States)

    Orsi Gordo, Vanessa; Herval, Leonilson Ks; Galeti, Helder Va; Gobato, Yara Galvão; Brasil, Maria Jsp; Marques, Gilmar E; Henini, Mohamed; Airey, Robert J

    2012-10-25

    We have studied the polarized resolved photoluminescence of n-type GaAs/AlAs/GaAlAs resonant tunneling diodes under magnetic field parallel to the tunnel current. Under resonant tunneling conditions, we have observed two emission lines attributed to neutral (X) and negatively charged excitons (X-). We have observed a voltage-controlled circular polarization degree from the quantum well emission for both lines, with values up to -88% at 15 T at low voltages which are ascribed to an efficient spin injection from the 2D gases formed at the accumulation layers.

  19. Light-emitting diodes - Their potential in biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, Naichia Gary; Wu, Chia-Hao [College of Applied Sciences, MingDao University, 369 Wen-Hua Road, Peetou, Changhua 52345 (China); Cheng, Ta Chih [Department of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology, 1 Hseuh-Fu Rd., Nei-Pu Hsiang, Pingtung 91201 (China)

    2010-10-15

    The rapid development of high brightness light-emitting diodes (LEDs) makes feasible the use of LEDs, among other light sources (such as laser, intense pulse light and other incoherent light systems), for medical treatment and light therapy. This paper provides a general review on red, green, blue, ultraviolet LED applications in photo rejuvenation and medical treatments of a variety of physical abnormalities, as well as the relief of stress, circadian rhythm disorders, and seasonal affective disorder. The review, concentrated in the papers published after 1990, intends to show that LEDs are well qualified to succeed its more energy demanding counterparts in the named areas and beyond. (author)

  20. Five-level Z-source diode-clamped inverter

    DEFF Research Database (Denmark)

    Gao, F.; Loh, Poh Chiang; Blaabjerg, Frede

    2010-01-01

    This study proposes a five-level Z-source diode-clamped inverter designed with two intermediate Z-source networks connected between the dc input sources and rear-end inverter circuitry. By partially shorting the Z-source networks, new operating states not previously reported for two-level Z......-source inverter are introduced here for operating the proposed inverter with voltage buck–boost energy conversion ability and five-level phase voltage switching. These characteristic features are in fact always ensured at the inverter terminal output by simply adopting a properly designed carrier modulation...

  1. Development of diode junction nuclear battery using 63Ni

    International Nuclear Information System (INIS)

    Ulmen, B.; Miley, G.H.; Desai, P.D.; Moghaddam, S.; Masel, R.I.

    2009-01-01

    The diode junction nuclear battery is a long-lived, high-energy-density, but low electrical current power source with many specialized applications. In this type of battery, nuclear radiation is directly converted to electric power. A model is described and used to design the device configuration. Details of fabrication and testing of a planar geometry battery with 63 Ni radiation source are described. The electron beam induced current (EBIC) measurement technique and CASINO Monte Carlo simulation code were employed to analyze the device performance. Finally, an improved design with 3-dimensional surface microstructures that will provide improved performance is presented. (author)

  2. High-power non linear frequency converted laser diodes

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Andersen, Peter E.; Hansen, Anders Kragh

    2015-01-01

    We present different methods of generating light in the blue-green spectral range by nonlinear frequency conversion of tapered diode lasers achieving state-of-the-art power levels. In the blue spectral range, we show results using single-pass second harmonic generation (SHG) as well as cavity enh...... enhanced sum frequency generation (SFG) with watt-level output powers. SHG and SFG are also demonstrated in the green spectral range as a viable method to generate up to 4 W output power with high efficiency using different configurations....

  3. Top-emitting organic light-emitting diodes.

    Science.gov (United States)

    Hofmann, Simone; Thomschke, Michael; Lüssem, Björn; Leo, Karl

    2011-11-07

    We review top-emitting organic light-emitting diodes (OLEDs), which are beneficial for lighting and display applications, where non-transparent substrates are used. The optical effects of the microcavity structure as well as the loss mechanisms are discussed. Outcoupling techniques and the work on white top-emitting OLEDs are summarized. We discuss the power dissipation spectra for a monochrome and a white top-emitting OLED and give quantitative reports on the loss channels. Furthermore, the development of inverted top-emitting OLEDs is described.

  4. Polarization methods for diode laser excitation of solid state lasers

    Science.gov (United States)

    Holtom, Gary R.

    2008-11-25

    A mode-locked laser employs a coupled-polarization scheme for efficient longitudinal pumping by reshaped laser diode bars. One or more dielectric polarizers are configured to reflect a pumping wavelength having a first polarization and to reflect a lasing wavelength having a second polarization. A Yb-doped gain medium can be used that absorbs light having a first polarization and emits light having a second polarization. Using such pumping with laser cavity dispersion control, pulse durations of less than 100 fs can be achieved.

  5. Investigation of phosphorescent blue organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Chien-Shu [Department of Electrical Engineering and Information Technology, Technical University of Braunschweig (Germany); Siemens AG, CT MM 1, Erlangen (Germany); Krause, Ralf [Department of Materials Science VI, University of Erlangen-Nuernberg (Germany); Siemens AG, CT MM 1, Erlangen (Germany); Kozlowski, Fryderyk; Hunze, Arvid [Siemens AG, CT MM 1, Erlangen (Germany); Kowalsky, Wolfgang [Department of Electrical Engineering and Information Technology, Technical University of Braunschweig (Germany)

    2008-07-01

    Recently, rapid development of phosphorescent materials has significantly improved the efficiency of organic light emitting diodes (OLEDs). By using efficient phosphorescent emitter materials white OLEDs with high power efficiency values could be demonstrated. But especially blue phosphorescent devices, due to stability issues, need to be further investigated und optimized. In this work, blue OLED devices based on the phosphorescent emitter FIrpic were investigated. Single-carrier hole-only as well as electron-only devices were fabricated and characterized to study the impact of charge carriers on device performance.

  6. Transport characteristics in Au/pentacene/Au diodes

    Science.gov (United States)

    Hayashi, Toshiaki; Naka, Akiyoshi; Hiroki, Masanobu; Yokota, Tomoyuki; Someya, Takao; Fujiwara, Akira

    2018-03-01

    We have used scanning and transmission electron microscopes (SEM and TEM) to study the structure of a pentacene thin film grown on a Au layer with and shown that it consists of randomly oriented amorphous pentacene clusters. We have also investigated the transport properties of amorphous pentacene in a metal-semiconductor-metal (MSM) diode structure and shown that the current is logarithmically proportional to the square root of the applied voltage, which indicates that transport occurs as the result of hopping between localized sites randomly distributed in space and energy.

  7. Magnetic field effect on pentacene-doped sexithiophene diodes

    Science.gov (United States)

    Pham, Song-Toan; Fayolle, Marine; Ohto, Tatsuhiko; Tada, Hirokazu

    2017-11-01

    We studied the effect of impurities on the magnetoresistance of sexithiophene-based diodes using impedance spectroscopy. The impurities were introduced by doping pentacene molecules into a sexithiophene film through a co-evaporation process. The pentacene molecules act as charge-scattering centers, which trigger the negative magnetoresistance of the device. This makes it possible to tune the value of magnetoresistance from positive to negative by increasing the applied voltage. The beneficial properties induced by impurities suggest a potential route to integrate additional functions into organic devices.

  8. Determination of illuminants representing typical white light emitting diodes sources

    DEFF Research Database (Denmark)

    Jost, S.; Ngo, M.; Ferrero, A.

    2017-01-01

    is to develop LED-based illuminants that describe typical white LED products based on their Spectral Power Distributions (SPDs). Some of these new illuminants will be recommended in the update of the CIE publication 15 on colorimetry with the other typical illuminants, and among them, some could be used......Solid-state lighting (SSL) products are already in use by consumers and are rapidly gaining the lighting market. Especially, white Light Emitting Diode (LED) sources are replacing banned incandescent lamps and other lighting technologies in most general lighting applications. The aim of this work...... to complement the CIE standard illuminant A for calibration use in photometry....

  9. Optimization of freeform lightpipes for light-emitting-diode projectors.

    Science.gov (United States)

    Fournier, Florian; Rolland, Jannick

    2008-03-01

    Standard nonimaging components used to collect and integrate light in light-emitting-diode-based projector light engines such as tapered rods and compound parabolic concentrators are compared to optimized freeform shapes in terms of transmission efficiency and spatial uniformity. We show that the simultaneous optimization of the output surface and the profile shape yields transmission efficiency within the étendue limit up to 90% and spatial uniformity higher than 95%, even for compact sizes. The optimization process involves a manual study of the trends for different shapes and the use of an optimization algorithm to further improve the performance of the freeform lightpipe.

  10. Deep modulation of second-harmonic light by wavelength detuning of a laser diode

    DEFF Research Database (Denmark)

    Christensen, Mathias; Hansen, Anders Kragh; Noordegraaf, Danny

    2017-01-01

    ) master oscillator power amplifier (MOPA) laser diode with separate electrical contacts for the MO and the PA. A modulation depth in excess of 97% from 0.1 Hz to 10 kHz is demonstrated. This is done by wavelength tuning of the laser diode using only a 40 mA adjustment of the current through the MO...

  11. High power CW output from low confinement asymmetric structure diode laser

    NARCIS (Netherlands)

    Iordache, G.; Buda, M.; Acket, G.A.; Roer, van de T.G.; Kaufmann, L.M.F.; Karouta, F.; Jagadish, C.; Tan, H.H.

    1999-01-01

    High power continuous wave output from diode lasers using low loss, low confinement, asymmetric structures is demonstrated. An asymmetric structure with an optical trap layer was grown by metal organic vapour phase epitaxy. Gain guided 50 µm wide stripe 1-3 mm long diode lasers were studied. 1.8 W

  12. Temperature effect on protection diode for plasma-process induced charging damage

    NARCIS (Netherlands)

    Wang, Zhichun; Scarpa, A.; Smits, Sander M.; Kuper, F.G.; Salm, Cora

    2002-01-01

    In this paper, the leakage current of different drain-well diodes for plasma-charging protection has been simulated at high temperature. The simulation shows that the high ambient temperature, especially during plasma deposition process, enormously enhances the efficacy of the protection diodes in

  13. Spin-polarized light-emitting diodes based on organic bipolar spin valves

    Science.gov (United States)

    Vardeny, Zeev Valentine; Nguyen, Tho Duc; Ehrenfreund, Eitan Avraham

    2017-10-25

    Spin-polarized organic light-emitting diodes are provided. Such spin-polarized organic light-emitting diodes incorporate ferromagnetic electrodes and show considerable spin-valve magneto-electroluminescence and magneto-conductivity responses, with voltage and temperature dependencies that originate from the bipolar spin-polarized space charge limited current.

  14. Effects of electron-irradiation on electrical properties of AgCa/Si Schottky diodes

    International Nuclear Information System (INIS)

    Harmatha, L.; Zizka, M.; Sagatova, A.; Nemec, M.; Hybler, P.

    2013-01-01

    This contribution presents the results of the current-voltage I-V and the capacitance-voltage C-V measurement on the Schottky diodes with the AgCa gate on the silicon n-type substrate. The Si substrate was irradiated by 5 MeV electrons with a different dose value before the Schottky diode preparation. (authors)

  15. Low-Temperature Deposition of Layered SnSe2 for Heterojunction Diodes

    KAUST Repository

    Serna, Martha I.; Hasan, Syed M. N.; Nam, S.; El Bouanani, Lidia; Moreno, Salvador; Choi, Hyunjoo; Alshareef, Husam N.; Minary-Jolandan, Majid; Quevedo-Lopez, Manuel A.

    2018-01-01

    vapor deposition and molecular beam epitaxy. The 2D SnSe films exhibit a mobility of ≈4.0 cm V s, and are successfully used to demonstrate SnSe/p-Si heterojunction diodes. The diodes show I /I ratios of 10-10 with a turn on voltage of <0.5 V

  16. Characterization of High-power Quasi-cw Laser Diode Arrays

    Science.gov (United States)

    Stephen, Mark A.; Vasilyev, Aleksey; Troupaki, Elisavet; Allan, Graham R.; Kashem, Nasir B.

    2005-01-01

    NASA s requirements for high reliability, high performance satellite laser instruments have driven the investigation of many critical components; specifically, 808 nm laser diode array (LDA) pump devices. Performance and comprehensive characterization data of Quasi-CW, High-power, laser diode arrays is presented.

  17. QUANTITATIVE DETECTION OF ENVIRONMENTALLY IMPORTANT DYES USING DIODE LASER/FIBER-OPTIC RAMAN

    Science.gov (United States)

    A compact diode laser/fiber-optic Raman spectrometer is used for quantitative detection of environmentally important dyes. This system is based on diode laser excitation at 782 mm, fiber optic probe technology, an imaging spectrometer, and state-of-the-art scientific CCD camera. ...

  18. Development of high performance Schottky barrier diode and its application to plasma diagnostics

    International Nuclear Information System (INIS)

    Fujita, Junji; Kawahata, Kazuo; Okajima, Shigeki

    1993-10-01

    At the conclusion of the Supporting Collaboration Research on 'Development of High Performance Detectors in the Far Infrared Range' carried out from FY1990 to FY1992, the results of developing Schottky barrier diode and its application to plasma diagnostics are summarized. Some remarks as well as technical know-how for the correct use of diodes are also described. (author)

  19. Effect of the Bit Rate on the Pulses of the Laser Diodes | Ayadi ...

    African Journals Online (AJOL)

    The qualities required for Laser Diodes are their spatial and temporal coherence, and their performance in terms modulation. This paper presents the effect data rate of optical pulses delivered by diode laser using software COMSIS. Two types of modulation have been considered: direct modulation and external modulation.

  20. Operation of a high-purity silicon diode alpha particle detector at 1.4 K

    International Nuclear Information System (INIS)

    Martoff, C.J.; Kaczanowicz, E.; Neuhauser, B.J.; Lopez, E.; Zhang, Y.; Ziemba, F.P.

    1991-01-01

    Detection of alpha particles at temperatures as low as 1.4 K was demonstrated using a specially fabricated Si diode. The diode was 475 mm 2 by 0.280 mm thick, fabricated from high-purity silicon with degenerately doped contacts. This is an important step toward development of dual-mode (ionization plus phonon) silicon detectors for low energy radiation. (orig.)

  1. Comparison of the noise performance of 10GHz QW and QD mode-locked laser diodes

    DEFF Research Database (Denmark)

    Carpintero, Guillermo; Thompson, Mark G.; Yvind, Kresten

    2010-01-01

    This paper reports the experimental characterization of the noise performance of a quantum dot and a quantum well 10GHz passive mode locked laser diodes.......This paper reports the experimental characterization of the noise performance of a quantum dot and a quantum well 10GHz passive mode locked laser diodes....

  2. Design and fabrication of metal-insulator-metal diode for high frequency applications

    Science.gov (United States)

    Azad, Ibrahim; Ram, Manoj K.; Goswami, D. Yogi; Stefanakos, Elias

    2017-02-01

    Metal-insulator-metal (MIM) diodes play significant role in high speed electronics where high frequency rectification is needed. Quantum based tunneling mechanism helps MIM diodes to rectify at high frequency signals. Rectenna, antenna coupled MIM diodes are becoming popular due to their potential use as IR detectors and energy harvesters. Because of small active area, MIM diodes could easily be incorporated into integrated circuits (IC's). The objective of the work is to design and develop MIM diodes for high frequency rectification. In this work, thin insulating layer of ZnO was fabricated using Langmuir-Blodgett (LB) technique which facilitates ultrathin thin, uniform and pinhole free fabrication of insulating layer. The ZnO layer was synthesized from organic precursor of zinc acetate layer. The optimization in the LB technique of fabrication process led to fabricate MIM diodes with high non-linearity and sensitivity. Moreover, the top and bottom electrodes as well as active area of the diodes were patterned using UV-tunneling conduction mechanism. The highest sensitivity of the diode was measured around 37 (A/W), and the rectification ratio was found around 36 under low applied bias at +/-100 mV.

  3. Nearest-IR superluminescent diodes with a 100-nm spectral width

    Energy Technology Data Exchange (ETDEWEB)

    Il' chenko, S N; Ladugin, M A; Marmalyuk, Aleksandr A; Yakubovich, S D

    2012-11-30

    This paper presents an experimental study of quantum well superluminescent diodes with an extremely thin (InGa)As active layer. Under cw injection, the output power of such diodes is several milliwatts, with a centre wavelength of 830 nm and emission bandwidth of about 100 nm. (letters)

  4. Visible laser and superluminescent diode based free space and underwater communications

    KAUST Repository

    Ooi, Boon S.

    2017-01-30

    We report on our recent progress in high-modulation-efficiency, InGaN-based integrated waveguide modulator-laser diodes (IWM-LDs), high-speed violet and blue emitting superluminescent diodes (SLDs), InGaN-based vertical-cavity surface-emitting lasers (VCSELs), and their applications for gigahertz laser based free-space and underwater wireless optical communications.

  5. Coordination compounds of rare-earth metals with organic ligands for electroluminescent diodes

    International Nuclear Information System (INIS)

    Katkova, M A; Bochkarev, Mikhail N; Vitukhnovsky, Alexey G

    2005-01-01

    Data on lanthanide coordination compounds with organic ligands used in the design of electroluminescent diodes are summarised and systematically represented. The molecular and electronic structures and spectroscopic characteristics of these compounds are considered. A comparative analysis of the properties of organic electroluminescent diodes with different compositions of emitting and conductive layers is presented.

  6. Pulse-modulated multilevel data storage in an organic ferroelectric resistive memory diode

    NARCIS (Netherlands)

    Lee, J.; Breemen, A.J.J.M. van; Khikhlovskyi, V.; Kemerink, M.; Janssen, R.A.J.; Gelinck, G.H.

    2016-01-01

    We demonstrate multilevel data storage in organic ferroelectric resistive memory diodes consisting of a phase-separated blend of P(VDF-TrFE) and a semiconducting polymer. The dynamic behaviour of the organic ferroelectric memory diode can be described in terms of the inhomogeneous field mechanism

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

    KAUST Repository

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

    2016-01-01

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

  8. Study of 4H-SiC junction barrier Schottky diode using field guard ring termination

    International Nuclear Information System (INIS)

    Feng-Ping, Chen; Yu-Ming, Zhang; Hong-Liang, Lü; Yi-Men, Zhang; Jian-Hua, Huang

    2010-01-01

    This paper reports that the 4H-SiC Schottky barrier diode, PiN diode and junction barrier Schottky diode terminated by field guard rings are designed, fabricated and characterised. The measurements for forward and reverse characteristics have been done, and by comparison with each other, it shows that junction barrier Schottky diode has a lower reverse current density than that of the Schottky barrier diode and a higher forward drop than that of the PiN diode. High-temperature annealing is presented in this paper as well to figure out an optimised processing. The barrier height of 0.79 eV is formed with Ti in this work, the forward drop for the Schottky diode is 2.1 V, with an ideality factor of 3.2, and junction barrier Schottky diode with blocking voltage higher than 400 V was achieved by using field guard ring termination. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

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

    Science.gov (United States)

    Maeda, Y

    1994-08-10

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

  10. New class of compact diode pumped sub 10 fs lasers for biomedical applications

    DEFF Research Database (Denmark)

    Le, T.; Mueller, A.; Sumpf, B.

    2016-01-01

    Diode-pumping Ti: sapphire lasers promises a new approach to low-cost femtosecond light sources. Thus in recent years much effort has been taken just to overcome the quite low power and low beam qualities of available green diodes to obtain output powers of several hundred milliwatts from a fs-la...

  11. Visible laser and superluminescent diode based free space and underwater communications

    KAUST Repository

    Ooi, Boon S.

    2017-01-01

    We report on our recent progress in high-modulation-efficiency, InGaN-based integrated waveguide modulator-laser diodes (IWM-LDs), high-speed violet and blue emitting superluminescent diodes (SLDs), InGaN-based vertical-cavity surface-emitting lasers (VCSELs), and their applications for gigahertz laser based free-space and underwater wireless optical communications.

  12. Temperature issues with white laser diodes, calculation and approach for new packages

    Science.gov (United States)

    Lachmayer, Roland; Kloppenburg, Gerolf; Stephan, Serge

    2015-01-01

    Bright white light sources are of significant importance for automotive front lighting systems. Today's upper class systems mainly use HID or LED light sources. As a further step laser diode based systems offer a high luminance, efficiency and allow the realization of new dynamic and adaptive light functions and styling concepts. The use of white laser diode systems in automotive applications is still limited to laboratories and prototypes even though announcements of laser based front lighting systems have been made. But the environment conditions for vehicles and other industry sectors differ from laboratory conditions. Therefor a model of the system's thermal behavior is set up. The power loss of a laser diode is transported as thermal flux from the junction layer to the diode's case and on to the environment. Therefor its optical power is limited by the maximum junction temperature (for blue diodes typically 125 - 150 °C), the environment temperature and the diode's packaging with its thermal resistances. In a car's headlamp the environment temperature can reach up to 80 °C. While the difference between allowed case temperature and environment temperature is getting small or negative the relevant heat flux also becomes small or negative. In early stages of LED development similar challenges had to be solved. Adapting LED packages to the conditions in a vehicle environment lead to today's efficient and bright headlights. In this paper the need to transfer these results to laser diodes is shown by calculating the diodes lifetimes based on the presented model.

  13. The amplitude modulation of laser diode emission with antireflection piezo films on mirrors

    International Nuclear Information System (INIS)

    Abrarov, S.M.; Karimov, Kh.S.; Akhmedov, Kh.M.

    2001-01-01

    Present article is devoted to amplitude modulation of laser diode emission with antireflection piezo films on mirrors. The modulator based on laser diode and the emission amplitude modulation of which is performed by electric field impact on antireflection piezo films applied on mirrors was studied.

  14. Short-Term Audiological Results of Diode Laser in Comparison with Manual Perforation in Stapes Surgery.

    Science.gov (United States)

    Hamerschmidt, Rogerio; Saab, Stephanie Sbizera; Carvalho, Bettina; Carmo, Carolina do

    2018-04-01

    Introduction  Diode laser is a new alternative in stapes surgery for otosclerosis. The present study is the first to compare the short-term results of the surgery performed using diode laser to those obtained through the conventional fenestration technique. Objective  To use audiometry to establish a comparative analysis between the functional results obtained through surgery for otosclerosis using diode laser and the conventional technique. Method  Audiometric evaluation of 12 patients submitted to stapes surgery for otosclerosis, using diode laser or conventional fenestration by needle and drills, between 2014 and 2015. Each group was composed of 6 patients. Pre and post-operative measures were compared for three months in both groups. The speech recognition threshold, the air and bone conduction threshold, as well as the gap between them at 500 Hz, 1 KHz, 2 KHz and 4 KHz were measured. Results  Significant difference in bone conduction and SRT was observed when compared post- and preoperative results in the diode group. However diode and conventional technique groups presented significant differences in air conduction and air-bone gap, suggesting that both can provide functional improvement. Conclusion  Laser stapedotomy is a safe technique with good results. Both laser surgery and the conventional technique have improved the hearing of patients with a discreet advantage for the diode laser. Further prospective and randomized clinical trials are required to disclose all possible benefits of the stapes surgery using diode laser.

  15. A high power gain switched diode laser oscillator and amplifier for the CEBAF polarized electron injector

    International Nuclear Information System (INIS)

    Poelker, M.; Hansknecht, J.

    1996-01-01

    The photocathode in the polarized electron source at Jefferson Lab is illuminated with pulsed laser light from a gain switched diode laser and diode optical amplifier. Laser pulse repetition rates up to 2,000 MHz, optical pulsewidths between 31 and 123 ps, and average power > 100 mW are demonstrated. The laser system is highly reliable and completely remotely controlled

  16. Development of Schottky diode detectors at Research Institute of Electrical Communication, Tohoku University

    International Nuclear Information System (INIS)

    Mizuno, K.; Ono, S.; Suzuki, T.; Daiku, Y.

    1982-01-01

    Schottky diode detectors are widely used as fast, sensitive submillimeter detectors in plasma physics, radio astronomy, frequency standards and so on. In this paper, the research on submillimeter Schottky diodes at Tohoku University is described. A brief description is given on the theoretical examination of diode parameters for video detection in design and on the fabrication of n/n + GaAs Schottky diode chips. Antennas for Schottky barrier diodes are discussed. Three types of antenna structures have been proposed, and used for whisker-contacted Schottky diodes so far. These are compared with each other for their frequency response and gain. The bicone type antenna is promising because of its larger frequency response, but the optimum design for this type of antenna has not yet sufficiently been obtained. As the application of Schottky barrier diodes, the intensity modulation of submillimeter laser and a quasi-optically coupled harmonic mixer have been studied. The modulation degree of about 4 % for HCN laser output has been so far obtained at the maximum modulation frequency of 2 GHz. Since 1976, a quasi-optically coupled harmonic mixer has been used with a Schottky diode in harmonic mixing between microwaves, millimeter waves, and submillimeter waves. (Wakatsuki, Y.)

  17. Numerical simulation on the energy spectrum of the electron beam generated by low-impedance diode and the influence of external magnetic field on diode impedance

    International Nuclear Information System (INIS)

    Liu Guozhi

    2003-01-01

    The energy spectrum of the electron beam generated by low-impedance diode and the influence of external magnetic field on the impedance of diode are studied numerically in this paper. The results show that the beam generated by the diode has an energy spread, even with constant applied voltage. Additionally, external magnetic field has great but reverse influence on the impedance of low-impedance diode, which is, according to the author's analysis, the result of the change of the electron's track due to external magnetic field. If the beam current is less than the critical one for self-pinch, the impedance will be constant with the variation of external magnetic field

  18. Use of tunnel diode for nanosecond pulse amplification; Utilisation de la diode tunnel pour l'amplification d'impulsions nanosecondes

    Energy Technology Data Exchange (ETDEWEB)

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

    1970-07-01

    In a first part, after a brief review of tunnel diode properties, the paper presents graphic and analytic investigations of series, shunt and compound connected tunnel diode amplifiers. A study of the noise problem is given. In a second part, practical realizations are described and results of measurements of their gain and noise characteristics are presented. (author) [French] Une premiere partie presente, apres une breve revue des proprietes de la diode tunnel, une etude graphique et analytique des amplificateurs a diode tunnel, pour les configurations serie, parallele et serie-parallele. Le bruit de fond y est egalement etudie. La seconde partie decrit quelques realisations pratiques et indique les resultats des mesures effectuees sur le gain et le bruit de fond. (auteur)

  19. Design and experimental testing of air slab caps which convert commercial electron diodes into dual purpose, correction-free diodes for small field dosimetry.

    Science.gov (United States)

    Charles, P H; Cranmer-Sargison, G; Thwaites, D I; Kairn, T; Crowe, S B; Pedrazzini, G; Aland, T; Kenny, J; Langton, C M; Trapp, J V

    2014-10-01

    Two diodes which do not require correction factors for small field relative output measurements are designed and validated using experimental methodology. This was achieved by adding an air layer above the active volume of the diode detectors, which canceled out the increase in response of the diodes in small fields relative to standard field sizes. Due to the increased density of silicon and other components within a diode, additional electrons are created. In very small fields, a very small air gap acts as an effective filter of electrons with a high angle of incidence. The aim was to design a diode that balanced these perturbations to give a response similar to a water-only geometry. Three thicknesses of air were placed at the proximal end of a PTW 60017 electron diode (PTWe) using an adjustable "air cap". A set of output ratios (ORDet (fclin) ) for square field sizes of side length down to 5 mm was measured using each air thickness and compared to ORDet (fclin) measured using an IBA stereotactic field diode (SFD). kQclin,Qmsr (fclin,fmsr) was transferred from the SFD to the PTWe diode and plotted as a function of air gap thickness for each field size. This enabled the optimal air gap thickness to be obtained by observing which thickness of air was required such that kQclin,Qmsr (fclin,fmsr) was equal to 1.00 at all field sizes. A similar procedure was used to find the optimal air thickness required to make a modified Sun Nuclear EDGE detector (EDGEe) which is "correction-free" in small field relative dosimetry. In addition, the feasibility of experimentally transferring kQclin,Qmsr (fclin,fmsr) values from the SFD to unknown diodes was tested by comparing the experimentally transferred kQclin,Qmsr (fclin,fmsr) values for unmodified PTWe and EDGEe diodes to Monte Carlo simulated values. 1.0 mm of air was required to make the PTWe diode correction-free. This modified diode (PTWeair) produced output factors equivalent to those in water at all field sizes (5-50 mm

  20. Heat transfer and structure stress analysis of micro packaging component of high power light emitting diode

    Directory of Open Access Journals (Sweden)

    Hsu Chih-Neng

    2013-01-01

    Full Text Available This paper focuses on the heat transfer and structural stress analysis of the micro- scale packaging structure of a high-power light emitting diode. The thermal-effect and thermal-stress of light emitting diode are determined numerically. Light emitting diode is attached to the silicon substrate through the wire bonding process by using epoxy as die bond material. The silicon substrate is etched with holes at the bottom and filled with high conductivity copper material. The chip temperature and structure stress increase with input power consumption. The micro light emitting diode is mounted on the heat sink to increase the heat dissipation performance, to decrease chip temperature, to enhance the material structure reliability and safety, and to avoid structure failure as well. This paper has successfully used the finite element method to the micro-scale light emitting diode heat transfer and stress concentration at the edges through etched holes.