Sample records for beam pumped semiconductor

  1. Electron beam pumped semiconductor laser (United States)

    Hug, William F. (Inventor); Reid, Ray D. (Inventor)


    Electron-beam-pumped semiconductor ultra-violet optical sources (ESUVOSs) are disclosed that use ballistic electron pumped wide bandgap semiconductor materials. The sources may produce incoherent radiation and take the form of electron-beam-pumped light emitting triodes (ELETs). The sources may produce coherent radiation and take the form of electron-beam-pumped laser triodes (ELTs). The ELTs may take the form of electron-beam-pumped vertical cavity surface emitting lasers (EVCSEL) or edge emitting electron-beam-pumped lasers (EEELs). The semiconductor medium may take the form of an aluminum gallium nitride alloy that has a mole fraction of aluminum selected to give a desired emission wavelength, diamond, or diamond-like carbon (DLC). The sources may be produced from discrete components that are assembled after their individual formation or they may be produced using batch MEMS-type or semiconductor-type processing techniques to build them up in a whole or partial monolithic manner, or combination thereof.

  2. Pulsed pumping of semiconductor disk lasers. (United States)

    Hempler, Nils; Hopkins, John-Mark; Kemp, Alan J; Schulz, Nico; Rattunde, Marcel; Wagner, Joachim; Dawson, Martin D; Burns, David


    Efficient operation of semiconductor disk lasers is demonstrated using uncooled and inexpensive 905nm high-power pulsed semiconductor pump lasers. Laser emission, with a peak power of 1.7W, is obtained from a 2.3mum semiconductor disk laser. This is seven times the power achieved under continuous pumping. Analysis of the time-dependent spectral characteristics of the laser demonstrate that significant device heating occurs over the 100-200ns duration of the pumping pulse - finite element modelling of the thermal processes is undertaken in support of these data. Spectral narrowing to below 0.8nm is obtained by using an intra-cavity birefringent filter.

  3. Coherent optical pumping of semiconductor lasers

    Energy Technology Data Exchange (ETDEWEB)

    Pfister, M.; Dupertuis, M.A. [Inst. de Micro- et Optoelectronique, Lausanne (Switzerland). Dept. de Physique


    The influence of coherent optical pumping in semiconductor lasers is investigated theoretically. In particular the mathematical conditions under which an optically pumped system behaves like an electrically (incoherently) pumped system are derived. The authors show that it is practically impossible to reach the interesting regime where coherent effects are important because of the inherent constraints to absorb photons at the pump frequency and to reach threshold gain at the lasing frequency. The effects of changing the temperature and of reduced dimensionality are discussed.

  4. DBR-free optically pumped semiconductor disk lasers (United States)

    Yang, Zhou; Albrecht, Alexander R.; Cederberg, Jeffrey G.; Sheik-Bahae, Mansoor


    Optically pumped semiconductor disk lasers (SDLs) provide high beam quality with high average-power power at designer wavelengths. However, material choices are limited by the need for a distributed Bragg reflector (DBR), usually monolithically integrated with the active region. We demonstrate DBR-free SDL active regions, which have been lifted off and bonded to various transparent substrates. For an InGaAs multi-quantum well sample bonded to a diamond window heat spreader, we achieved CW lasing with an output power of 2 W at 1150 nm with good beam quality.

  5. Nonlinear fibre-optic devices pumped by semiconductor disk lasers

    Energy Technology Data Exchange (ETDEWEB)

    Chamorovskiy, A Yu; Okhotnikov, Oleg G [Optoelectronics Research Center, Tampere University of Technology, Tampere (Finland)


    Semiconductor disk lasers offer a unique combination of characteristics that are particularly attractive for pumping Raman lasers and amplifiers. The advantages of disk lasers include a low relative noise intensity (-150 dB Hz{sup -1}), scalable (on the order of several watts) output power, and nearly diffraction-limited beam quality resulting in a high ({approx}70 % - 90 %) coupling efficiency into a single-mode fibre. Using this technology, low-noise fibre Raman amplifiers operating at 1.3 {mu}m in co-propagation configuration are developed. A hybrid Raman-bismuth doped fibre amplifier is proposed to further increase the pump conversion efficiency. The possibility of fabricating mode-locked picosecond fibre lasers operating under both normal and anomalous dispersion is shown experimentally. We demonstrate the operation of 1.38-{mu}m and 1.6-{mu}m passively mode-locked Raman fibre lasers pumped by 1.29-{mu}m and 1.48-{mu}m semiconductor disk lasers and producing 1.97- and 2.7-ps pulses, respectively. Using a picosecond semiconductor disk laser amplified with an ytterbium-erbium fibre amplifier, the supercontinuum generation spanning from 1.35 {mu}m to 2 {mu}m is achieved with an average power of 3.5 W. (invited paper)

  6. Spherical distribution structure of the semiconductor laser diode stack for pumping

    Institute of Scientific and Technical Information of China (English)

    Zhao Tianzhuo; Yu Jin; Liu Yang; Zhang Xue; Ma Yunfeng; Fan Zhongwei


    A semiconductor laser diode stack is used for pumping and 8 semiconductor laser diode arrays of the stack are put on a sphere,and the output of every bar is specially off-axis compressed to realize high coupling efficiency.The output beam of this semiconductor laser diode stack is shaped by a hollow duct to the laser active medium.The efficiency of the hollow light pipe,which is used for semiconductor laser diode stack coupling,is analyzed by geometric optics and ray tracing.Geometric optics analysis diagnoses the reasons for coupling loss and guides the design of the structure.Ray tracing analyzes the relation between the structural parameters and the output characteristics of this pumping system,and guides parameter optimization.Simulation and analysis results show that putting the semiconductor laser diode arrays on a spherical surface can increase coupling efficiency,reduce the optimum duct length and improve the output energy field distribution.

  7. Low-noise Raman fiber amplifier pumped by semiconductor disk laser. (United States)

    Chamorovskiy, A; Rautiainen, J; Rantamäki, A; Okhotnikov, O G


    A 1.3 µm Raman fiber amplifier pumped by 1.22 µm semiconductor disk laser in co-propagation geometry is demonstrated. Measured relative intensity noise of -148 dB/Hz over frequency range up to 3.5 GHz was measured at 900 mW of pump power. 9 dB gain was achieved with co-propagating pumping geometry with less than 2 dB additional noise induced by amplifier to the signal. Nearly shot-noise-limited operation of semiconductor disk laser combined with the diffraction-limited beam allows for efficient core-pumping of the single-mode fiber Raman amplifiers and represents a highly practical approach which takes full advantage of co-propagating pumping.

  8. 1.3 µm Raman-bismuth fiber amplifier pumped by semiconductor disk laser. (United States)

    Chamorovskiy, A; Rautiainen, J; Rantamäki, A; Golant, K M; Okhotnikov, O G


    A hybrid Raman-bismuth fiber amplifier pumped in co-propagation configuration by a single 1.22 µm semiconductor disk laser is presented. The unique attribute of this dual-gain system is that both amplifiers require the pump source with the same wavelength because pump-Stokes spectral shift in 1.3 µm Raman amplifier and pump-gain bandwidth separation in 1.3 µm bismuth fiber amplifier have the same value. Residual pump power at the output of Raman amplifier in this scheme is efficiently consumed by bismuth-doped fiber thus increasing the overall conversion efficiency. The small-signal gain of 18 dB at 1.3 W of pump power has been achieved for hybrid scheme which is by 9 dB higher as compared with isolated Raman amplifier without bismuth fiber. Low noise performance of pump semiconductor disk laser with RIN of -150 dB/Hz combined with nearly diffraction-limited beam quality and Watt-level output powers allows for efficient core-pumping of a single-mode fiber amplifier systems and opens up new opportunities for amplification in O-band spectral range.

  9. Semiconductor disk laser pumped Cr2+:Znse lasers. (United States)

    Hempler, Nils; Hopkins, John-Mark; Rösener, Benno; Rattunde, Marcel; Wagner, Joachim; Fedorov, Vladimir V; Moskalev, Igor S; Mirov, Sergey B; Burns, David


    A new flexible pump source, the optically-pumped semiconductor disk laser (SDL), for the Cr(2+):ZnSe laser is reported. The SDL provides up to 6W output power at a free running central wavelength of 1.98 microm. The Cr(2+):ZnSe laser operated at an output power of 1.8W and a slope efficiency of approximately 50% with respect to absorbed pump power whilst maintaining a low output intensity noise figure of <0.14% RMS. The system required no optical isolation even under the situation of significant optical feedback.

  10. Electronic displays using optically pumped luminescent semiconductor nanocrystals (United States)

    Weiss, Shimon; Schlamp, Michael C.; Alivisatos, A. Paul


    A multicolor electronic display is based on an array of luminescent semiconductor nanocrystals. Nanocrystals which emit light of different colors are grouped into pixels. The nanocrystals are optically pumped to produce a multicolor display. Different sized nanocrystals are used to produce the different colors. A variety of pixel addressing systems can be used.

  11. Electronic displays using optically pumped luminescent semiconductor nanocrystals (United States)

    Weiss, Shimon; Schlam, Michael C; Alivisatos, A. Paul


    A multicolor electronic display is based on an array of luminescent semiconductor nanocrystals. Nanocrystals which emit tight of different colors are grouped into pixels. The nanocrystals are optically pumped to produce a multicolor display. Different sized nanocrystals are used to produce the different colors. A variety of pixel addressing systems can be used.

  12. Superfluorescent emission in electrically pumped semiconductor laser

    CERN Document Server

    Boiko, D L; Stadelmann, T; Grossmann, S; Hoogerwerf, A; Weig, T; Schwarz, U T; Sulmoni, L; Lamy, J -M; Grandjean, N


    We report superfluorescent (SF) emission in electrically pumped InGaN/InGaN QW lasers with saturable absorber. In particular, we observe a superlinear growth of the peak power of SF pulses with increasing amplitude of injected current pulses and attribute it to cooperative pairing of electron-hole (e-h) radiative recombinations. The phase transitions from amplified spontaneous emission to superfluorescence and then to lasing regime is confirmed by observing (i) superlinear peak power growth, (ii) spectral shape with hyperbolic secant envelope and (iii) red shift of central wavelength of SF emission pulse. The observed red shift of SF emission is shown to be caused by the pairing of e-h pairs in an indirect cooperative X-transition.

  13. The Electron Beam Semiconductor (EBS) amplifier (United States)

    True, R. M.; Baxendale, J. F.


    The Electron Beam Semiconductor (EBS) concept has existed for three decades; but only within the last decade has an active, well-defined program been underway to develop devices that can operate as high-power radio frequency(RF) amplifiers, fast risetime switches, and current and voltage pulse amplifiers. This report discusses the test procedures, data and results of reliability testing of RF and video pulse EBS amplifiers at Electronics Research and Development Command (ERADCOM), Fort Monmouth, New Jersey. Also, the experimental analysis of the series connected diode EBS device is described in detail. Finally, the report concludes with a discussion of the state-of-the-art of EBS and future trends of the technology.

  14. Gigahertz dual-comb modelocked diode-pumped semiconductor and solid-state lasers (United States)

    Link, S. M.; Mangold, M.; Golling, M.; Klenner, A.; Keller, U.


    We present a simple approach to generate simultaneously two gigahertz mode-locked pulse trains from a single gain element. A bi-refringent crystal in the laser cavity splits the one cavity beam into two cross-polarized and spatially separated beams. This polarization-duplexing is successfully demonstrated for both a semiconductor disk laser (i.e. MIXSEL) and a diode-pumped solid-state Nd:YAG laser. The beat between the two beams results in a microwave frequency comb, which represents a direct link between the terahertz optical frequencies and the electronically accessible microwave regime. This dual-output technique enables compact and cost-efficient dual-comb lasers for spectroscopy applications.

  15. Semiconductor Laser Diode Pumps for Inertial Fusion Energy Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Deri, R J


    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 {approx} 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

  16. Development of optically pumped DBR-free semiconductor disk lasers (Conference Presentation) (United States)

    Yang, Zhou; Albrecht, Alexander R.; Cederberg, Jeffrey G.; Sheik-Bahae, Mansoor


    Semiconductor disk lasers (SDLs) are attractive for applications requiring good beam quality, wavelength versatility, and high output powers. Typical SDLs utilize the active mirror geometry, where a semiconductor DBR is integrated with the active region by growth or post-growth bonding. This imposes restrictions for the SDL design, like material system choice, thermal management, and effective gain bandwidth. In DBR-free geometry, these restrictions can be alleviated. An integrated gain model predicts DBR-free geometry with twice the gain bandwidth of typical SDLs, which has been experimentally verified with active regions near 1 μm and 1.15 μm. The lift-off and bonding technique enables the integration of semiconductor active regions with arbitrary high quality substrates, allowing novel monolithic geometries. Bonding an active region onto a straight side of a commercial fused silica right angle prism, and attaching a high reflectivity mirror onto the hypotenuse side, with quasi CW pumping at 780 nm, lasing operation was achieved at 1037 nm with 0.2 mW average power at 1.6 mW average pump power. Laser dynamics show that thermal lens generation in the active region bottlenecks the laser efficiency. Investigations on total internal reflection based monolithic ring cavities are ongoing. These geometries would allow the intracavity integration of 2D materials or other passive absorbers, which could be relevant for stable mode locking. Unlike typical monolithic microchip SDLs, with the evanescent wave coupling technique, these monolithic geometries allow variable coupling efficiency.

  17. External cavity beam combining of 21 semiconductor lasers using SPGD. (United States)

    Montoya, Juan; Augst, Steven J; Creedon, Kevin; Kansky, Jan; Fan, Tso Yee; Sanchez-Rubio, Antonio


    Active coherent beam combining of laser oscillators is an attractive way to achieve high output power in a diffraction limited beam. Here we describe an active beam combining system used to coherently combine 21 semiconductor laser elements with an 81% beam combining efficiency in an external cavity configuration compared with an upper limit of 90% efficiency in the particular configuration of the experiment. Our beam combining system utilizes a stochastic parallel gradient descent (SPGD) algorithm for active phase control. This work demonstrates that active beam combining is not subject to the scaling limits imposed on passive-phasing systems.

  18. Two-Photon-Pumped Perovskite Semiconductor Nanocrystal Lasers. (United States)

    Xu, Yanqing; Chen, Qi; Zhang, Chunfeng; Wang, Rui; Wu, Hua; Zhang, Xiaoyu; Xing, Guichuan; Yu, William W; Wang, Xiaoyong; Zhang, Yu; Xiao, Min


    Two-photon-pumped lasers have been regarded as a promising strategy to achieve frequency up-conversion for situations where the condition of phase matching required by conventional approaches cannot be fulfilled. However, their practical applications have been hindered by the lack of materials holding both efficient two-photon absorption and ease of achieving population inversion. Here, we show that this challenge can be tackled by employing colloidal nanocrystals of perovskite semiconductors. We observe highly efficient two-photon absorption (with a cross section of 2.7 × 10(6) GM) in toluene solutions of CsPbBr3 nanocrystals that can excite large optical gain (>500 cm(-1)) in thin films. We have succeeded in demonstrating stable two-photon-pumped lasing at a remarkable low threshold by coupling CsPbBr3 nanocrystals with microtubule resonators. Our findings suggest perovskite nanocrystals can be used as excellent gain medium for high-performance frequency-up-conversion lasers toward practical applications.

  19. Photorefractive dynamic holography using self-pumped phase conjugate beam

    Indian Academy of Sciences (India)

    Arun Anand; C S Narayanamurthy


    Dynamic holography in photorefractive materials using self-pumped phase conjugate beam of the object beam itself as the other writing beam is proposed. Our detailed theoretical analysis shows four-fold increase in the diffraction efficiency of dynamic holograms if recorded using this geometry even in photorefractive crystal like BTO (having low optical activity) without applying external field. Detailed theoretical analysis is given.

  20. [Initial research of one-beam pumping up-conversion 3D volumetric display based on Er:ZBLAN glass]. (United States)

    Chen, Xiao-bo; Li, Mei-xian; Wen, Ou; Zhang, Fu-chu; Song, Zeng-fu


    This paper investigates one-beam pumping up-conversion three-dimensional volumetric display, which is based on a Er:ZBLAN fluoride glass. The light-length of the facula of one-beam up-conversion luminescence was studied by a 966 nm semiconductor laser. The up-conversion luminescence spectrum was also obtained. It was found that the property of one-beam pumping three-dimensional volumetric display can be improved significantly by 1.52 microns LD laser multi-photon up-conversion, this finding has not been reported.

  1. Synchronous Characterization of Semiconductor Microcavity Laser Beam

    CERN Document Server

    Wang, Tao


    We report on a high-resolution double-channel imaging method used to synchronously map the intensity- and optical-frequency-distribution of a laser beam in the plane orthogonal to the propagation direction. The synchronous measurement allows us to show that the laser frequency is an inhomogeneous distribution below threshold, but that it becomes homogeneous across the fundamental Gaussian mode above threshold. The beam's tails deviations from the Gaussian shape, however, are accompanied by sizeable fluctuations in the laser wavelength, possibly deriving from manufacturing details and from the influence of spontaneous emission in the very low intensity wings. In addition to the synchronous spatial characterization, a temporal analysis at any given point in the beam cross-section is carried out. Using this method, the beam homogeneity and spatial shape, energy density, energy center and the defects-related spectrum can also be extracted from these high-resolution pictures.

  2. Lasing and ion beam doping of semiconductor nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Geburt, Sebastian


    Semiconductor nanowires exhibit extraordinary optical properties like highly localized light emission, efficient waveguiding and light amplification. Even the stimulation of laser oscillations can be achieved at optical pumping, making nanowires promising for optoelectronic applications. For successful integration into future devices, three major key challenges have to be faced: (1) the understanding of the fundamental properties, (2) the modification of the emission characteristics and (3) the investigation of the efficiency-limiting factors. All key challenges are addressed in this thesis: (1) The fundamental properties of CdS nanowire have been investigated to uncover the size limits for photonic nanowire lasers. Laser oscillations were observed at room temperature and the emission characteristics were correlated to the morphology, which allowed the determination of a minimum diameter and length necessary for lasing. (2) The emission characteristics of ZnO nanowires have been successfully modified by ion beam doping with Co. The structural investigations revealed a good recovery of the ion induced damage in the crystal lattice. Optical activation of the implanted Co ions was achieved and an intense intra-3d-emission confirmed successful modification. (3) The temporal decay of excited luminescence centers strongly depends on the interplay of luminescent ions and defects, thus offering an approach to investigate the efficiency-limiting processes. Mn implanted ZnS nanowires were investigated, as the temporal decay of the incorporated Mn ions can be described by a Foerster energy transfer model modified for nanostructures. The defect concentration was varied systematically by several approaches and the model could successfully fit the transients in all cases. The emission properties of Tb implanted ZnS nanowires were investigated and the temporal decay of the intra-4f-emission could also be fitted by the model, proving its accuracy for an additional element.

  3. Quantum transport of the semiconductor pump: Due to an axial external field

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Yun-Chang, E-mail: [College of Electrical and Information Engineering, Hunan University of Arts and Science, Changde 415000 (China); Wang, Ri-Xing, E-mail: [College of Electrical and Information Engineering, Hunan University of Arts and Science, Changde 415000 (China); Deng, Wei-Ying, E-mail: [Department of Physics, South China University of Technology, Guangzhou 510640 (China)


    Parametric semiconductor pump modulated by the external field is investigated. The pump center attaching to two normal leads is driven by the potentials formed in the interfaces. With the Floquet scattering matrix method, the pumped currents modulated by the parameters are studied. Results reveal that the charge and spin currents pumped from the system can be strengthen by the external field besides the potentials. Directed spin currents can be pumped more strongly than the charge currents, and even the pure spin currents can be achieved in some external field couplings to the pump parameters.

  4. Electrically pumped photonic crystal laser constructed with organic semiconductors (United States)

    Cai, Yuan-yuan; Chen, Xiao; Li, Ning; Li, Chang-wei; Wang, Yi-quan


    We experimentally demonstrate the lasing action of electrically pumped octagonal quasi-crystal microcavities formed in a layer of conjugated polymer poly[2-methoxy- 5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) sandwiched between two electrodes. Lasing from a point-defect microcavity is observed at a wavelength of 606 nm with a narrow linewidth of 0.5 nm, limited by the spectrometer resolution. Due to the properties of the photonic bandgap and localization in photonic crystals, the threshold current for lasing is low at 0.8 mA. The ion injection in the luminescent polymer layer by focused ion beam (FIB) etching technology also contributes to enhancement of the carrier density as well as the mobility, resulting in an increase of MEH-PPV conductivity and a decrease of turn-on voltage.

  5. Electron beam generation from semiconductor photocathodes (United States)

    Arneodo, F.; Cavanna, F.; De Mitri, I.; Mazza, D.; Nassisi, V.


    Several measurements on a variety of semiconductor photocathodes were performed in order to determine their photoelectric quantum efficiency. Two different excimer lasers (XeCl and KrCl) and a pulsed Xe lamp were used as light sources for electron photoextraction from doped and undoped samples of cadmiun telluride, indium antimonide, and indium phosphide. Large current densities were obtained up to the limit of the Child-Langmuir law. This suggests the use of these materials for the production of intense electron sources, which could also be used for purity measurements of noble liquids.

  6. Simulation of a tunable optically pumped terahertz intersubband laser with diluted magnetic semiconductors

    NARCIS (Netherlands)

    Popadić, M.; Milanović, V.; Ikonić, Z.; Indijn, D.


    A simulation of an optically pumped laser based on a ZnSe/Zn1−yCdySe double quantum well with a Zn1−xMnxSe diluted magnetic semiconductor barrier is presented. Giant Zeeman splitting in diluted magnetic semiconductors leads to splitting of electronic states, which in turn leads to tunability of lase

  7. Low threshold diode-pumped picosecond mode-locked Nd:YAG laser with a semiconductor saturable absorber mirror (United States)

    Eshghi, M. J.; Majdabadi, A.; Koohian, A.


    In this paper, a low threshold diode pumped passively mode-locked Nd:YAG laser has been demonstrated by using a semiconductor saturable absorber mirror. The threshold power for continuous-wave mode-locking is relatively low, about 3.2 W. The resonator stability across the pump power has been analytically examined. Moreover, the mode overlap between the pump beam and the laser fundamental mode has been simulated by MATLAB software. Adopting Z-shaped resonator configuration and suitable design of the resonator’s arm lengths, has enabled the author to prepare mode-locking conditions, and obtain 40 ps pulses with 112 MHz pulse repetition rate. The laser output was stable without any Q switched instability. To the best of our knowledge, this is the lowest threshold for CW mode-locking operation of a Nd:YAG laser.

  8. Pumping slots and thickness of the LHC beam screen

    CERN Document Server

    Mostacci, A


    RF losses through the pumping slots in the LCH beam screen scale exponentially with the ratio of screen thickness to slot width. We present numeric results in graphic form and a simplified analytic fit that can be useful to further optimise the beam screen design. This note is based on a minor revision of CERN LHC Project Report 199

  9. Continuous-wave Raman laser pumped within a semiconductor disk laser cavity. (United States)

    Parrotta, Daniele C; Lubeigt, Walter; Kemp, Alan J; Burns, David; Dawson, Martin D; Hastie, Jennifer E


    A KGd(WO₄)₂ Raman laser was pumped within the cavity of a cw diode-pumped InGaAs semiconductor disk laser (SDL). The Raman laser threshold was reached for 5.6 W of absorbed diode pump power, and output power up to 0.8 W at 1143 nm, with optical conversion efficiency of 7.5% with respect to the absorbed diode pump power, was demonstrated. Tuning the SDL resulted in tuning of the Raman laser output between 1133 and 1157 nm.

  10. Modeling and simulation performance of sucker rod beam pump (United States)

    Aditsania, Annisa; Rahmawati, Silvy Dewi; Sukarno, Pudjo; Soewono, Edy


    Artificial lift is a mechanism to lift hydrocarbon, generally petroleum, from a well to surface. This is used in the case that the natural pressure from the reservoir has significantly decreased. Sucker rod beam pumping is a method of artificial lift. Sucker rod beam pump is modeled in this research as a function of geometry of the surface part, the size of sucker rod string, and fluid properties. Besides its length, sucker rod string also classified into tapered and un-tapered. At the beginning of this research, for easy modeling, the sucker rod string was assumed as un-tapered. The assumption proved non-realistic to use. Therefore, the tapered sucker rod string modeling needs building. The numerical solution of this sucker rod beam pump model is computed using finite difference method. The numerical result shows that the peak of polished rod load for sucker rod beam pump unit C-456-D-256-120, for non-tapered sucker rod string is 38504.2 lb, while for tapered rod string is 25723.3 lb. For that reason, to avoid the sucker rod string breaks due to the overload, the use of tapered sucker rod beam string is suggested in this research.

  11. Modeling and simulation performance of sucker rod beam pump

    Energy Technology Data Exchange (ETDEWEB)

    Aditsania, Annisa, E-mail: [Department of Computational Sciences, Institut Teknologi Bandung (Indonesia); Rahmawati, Silvy Dewi, E-mail:; Sukarno, Pudjo, E-mail: [Department of Petroleum Engineering, Institut Teknologi Bandung (Indonesia); Soewono, Edy, E-mail: [Department of Mathematics, Institut Teknologi Bandung (Indonesia)


    Artificial lift is a mechanism to lift hydrocarbon, generally petroleum, from a well to surface. This is used in the case that the natural pressure from the reservoir has significantly decreased. Sucker rod beam pumping is a method of artificial lift. Sucker rod beam pump is modeled in this research as a function of geometry of the surface part, the size of sucker rod string, and fluid properties. Besides its length, sucker rod string also classified into tapered and un-tapered. At the beginning of this research, for easy modeling, the sucker rod string was assumed as un-tapered. The assumption proved non-realistic to use. Therefore, the tapered sucker rod string modeling needs building. The numerical solution of this sucker rod beam pump model is computed using finite difference method. The numerical result shows that the peak of polished rod load for sucker rod beam pump unit C-456-D-256-120, for non-tapered sucker rod string is 38504.2 lb, while for tapered rod string is 25723.3 lb. For that reason, to avoid the sucker rod string breaks due to the overload, the use of tapered sucker rod beam string is suggested in this research.

  12. Persistent ion beam induced conduction in semiconductor nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Johannes, Andreas; Niepelt, Raphael; Gnauck, Martin; Slowik, Irma; Thielmann, Andreas; Geburt, Sebastian; Schroeder, Ulrich; Stoll, David; Ronning, Carsten [Institut fuer Festkoerper Physik, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, 07743 (Germany)


    The electrical conductance of single, semiconductor nanowires is investigated in-situ during ion beam exposure. A stark increase in conductance proportional to ion flux and ion energy is observed. The increase in conductance shows remarkable similarities to the persistent photoconduction effect (PPC), which is well known yet not comprehensively understood. Especially ZnO nanowires show a strong increase in conductance (photo and ion induced) that only decays over days. Experiments are performed to investigate the parallels between ion and photo induced conductivity and to examine the underlying mechanisms. The decay rate is very sensitive to the external environment so that surface effects are considered to cause the conduction enhancement.

  13. Load beam unit replaceable inserts for dry coal extrusion pumps (United States)

    Saunders, Timothy; Brady, John D.


    A track assembly for a particulate material extrusion pump according to an exemplary aspect of the present disclosure includes a link assembly with a roller bearing. An insert mounted to a load beam located such that the roller bearing contacts the insert.

  14. DPSS Laser Beam Quality Optimization Through Pump Current Tuning

    Energy Technology Data Exchange (ETDEWEB)

    Omohundro, Rob; /Newport Spectra-Physics, Santa Clara; Callen, Alice; /SLAC; Sukuta, Sydney; /San Jose City Coll.


    The goal of this study is to demonstrate how a DPSS laser beam's quality parameters can be simultaneously optimized through pump current tuning. Two DPSS lasers of the same make and model were used where the laser diode pump current was first varied to ascertain the lowest RMS noise region. The lowest noise was found to be 0.13% in this region and the best M{sup 2} value of 1.0 and highest laser output power were simultaneously attained at the same current point. The laser manufacturer reported a M{sup 2} value of 1.3 and RMS noise value of .14% for these lasers. This study therefore demonstrates that pump current tuning a DPSS laser can simultaneously optimize RMS Noise, Power and M{sup 2} values. Future studies will strive to broaden the scope of the beam quality parameters impacted by current tuning.

  15. Runaway electron beam control for longitudinally pumped metal vapor lasers (United States)

    Kolbychev, G. V.; Kolbycheva, P. D.


    Physics and techniques for producing of the pulsed runaway electron beams are considered. The main obstacle for increasing electron energies in the beams is revealed to be a self- breakdown of the e-gun's gas-filled diode. Two methods to suppress the self-breakdown and enhance the volumetric discharge producing the e-beam are offered and examined. Each of them provides 1.5 fold increase of the ceiling potential on the gun. The methods also give the ways to control several guns simultaneously. Resulting in the possibility of realizing the powerful longitudinal pumping of metal-vapor lasers on self-terminated transitions of atoms or ions.

  16. Semiconductor characterization by scanning ion beam induced charge (IBIC) microscopy

    CERN Document Server

    Vittone, E; Olivero, P; Manfredotti, C; Jaksic, M; Giudice, A Lo; Fizzotti, F; Colombo, E


    The acronym IBIC (Ion Beam Induced Charge) was coined in early 1990's to indicate a scanning microscopy technique which uses MeV ion beams as probes to image the basic electronic properties of semiconductor materials and devices. Since then, IBIC has become a widespread analytical technique to characterize materials for electronics or for radiation detection, as testified by more than 200 papers published so far in peer-reviewed journals. Its success stems from the valuable information IBIC can provide on charge transport phenomena occurring in finished devices, not easily obtainable by other analytical techniques. However, IBIC analysis requires a robust theoretical background to correctly interpret experimental data. In order to illustrate the importance of using a rigorous mathematical formalism, we present in this paper a benchmark IBIC experiment aimed to test the validity of the interpretative model based on the Gunn's theorem and to provide an example of the analytical capability of IBIC to characteriz...

  17. Polarization measurement of Cs using the pump laser beam

    CERN Document Server

    Fang, Jiancheng; Duan, Lihong; Fan, Wenfeng; Jiang, Liwei


    In the optical pumping systems based on the pump-probe arrangement, the spin polarization of the atoms is generally monitored utilizing the probe laser beam, in which way an extra perturbation must be introduced and thus affects the normal operation of the sensors. By investigating the absorption rate of the circularly polarized pump laser, here we demonstrate the feasibility of extracting the electron-spin polarization from the transmitted pump laser intensity. We experimentally validate the method in a spin-exchange relaxation free (SERF) magnetometer and the results are in excellent agreement with the theory. The scheme operates in a silent mode and features a real-time observation. We also study the corresponding magnetic field response of the SERF magnetometer and a term arising from the diffusion effects has been added to the original model to explain the discrepancy of the response.

  18. Picosecond pulse generation from a synchronously pumped mode-locked semiconductor laser diode (United States)

    Auyeung, J. C.; Johnston, A. R.


    A semiconductor laser diode was mode locked in an external cavity when synchronously pumped with 90-ps current pulses. Transform-limited optical pulses with a 10-ps pulse width and a peak power of 160 mW were produced. Operating characteristics of such a system are described.

  19. High-power optically pumped semiconductor laser apllications (United States)

    Morioka, S. Brandon


    OPS lasers have found applications in various industrial and scientific laser applications due to their power scaling capability, their wide range of emission wavelengths, physical size and their superior reliability. This paper provides an overview of commercially available OPS lasers and the applications in which they are used including biotechnology, medical, holography, Titanium-Sapphire laser pumping, non-lethal defense, forensics, and entertainment.

  20. An Energy Saving System for a Beam Pumping Unit

    Directory of Open Access Journals (Sweden)

    Hongqiang Lv


    Full Text Available Beam pumping units are widely used in the oil production industry, but the energy efficiency of this artificial lift machinery is generally low, especially for the low-production well and high-production well in the later stage. There are a number of ways for energy savings in pumping units, with the periodic adjustment of stroke speed and rectification of balance deviation being two important methods. In the paper, an energy saving system for a beam pumping unit (ESS-BPU based on the Internet of Things (IoT was proposed. A total of four types of sensors, including load sensor, angle sensor, voltage sensor, and current sensor, were used to detect the operating conditions of the pumping unit. Data from these sensors was fed into a controller installed in an oilfield to adjust the stroke speed automatically and estimate the degree of balance in real-time. Additionally, remote supervision could be fulfilled using a browser on a computer or smartphone. Furthermore, the data from a practical application was recorded and analyzed, and it can be seen that ESS-BPU is helpful in reducing energy loss caused by unnecessarily high stroke speed and a poor degree of balance.

  1. An Energy Saving System for a Beam Pumping Unit. (United States)

    Lv, Hongqiang; Liu, Jun; Han, Jiuqiang; Jiang, An


    Beam pumping units are widely used in the oil production industry, but the energy efficiency of this artificial lift machinery is generally low, especially for the low-production well and high-production well in the later stage. There are a number of ways for energy savings in pumping units, with the periodic adjustment of stroke speed and rectification of balance deviation being two important methods. In the paper, an energy saving system for a beam pumping unit (ESS-BPU) based on the Internet of Things (IoT) was proposed. A total of four types of sensors, including load sensor, angle sensor, voltage sensor, and current sensor, were used to detect the operating conditions of the pumping unit. Data from these sensors was fed into a controller installed in an oilfield to adjust the stroke speed automatically and estimate the degree of balance in real-time. Additionally, remote supervision could be fulfilled using a browser on a computer or smartphone. Furthermore, the data from a practical application was recorded and analyzed, and it can be seen that ESS-BPU is helpful in reducing energy loss caused by unnecessarily high stroke speed and a poor degree of balance.

  2. Polarization/Spatial Combining of Laser-Diode Pump Beams (United States)

    Gelsinger, Paul; Liu, Duncan


    A breadboard version of an optical beam combiner is depicted which make it possible to use the outputs of any or all of four multimode laser diodes to pump a non-planar ring oscillator (NPRO) laser. The output of each laser diode has a single-mode profile in the meridional plane containing an axis denoted the 'fast' axis and a narrower multimode profile in the orthogonal meridional plane, which contains an axis denoted the 'slow' axis and a narrower multimode profile in the orthogonal meridional plane, which contains an axis denoted the 'slow' axis. One of the purposes served by the beam-combining optics is to reduce the fast-axis numerical aperture (NA) of the laser-diode output to match the NA of the optical fiber. Along the slow axis, the unmodified laser-diode NA is already well matched to the fiber optic NA, so no further slow-axis beam shaping is needed. In this beam combiner, the laser-diode outputs are collimated by aspherical lenses, then half-wave plates and polarizing beam splitters are used to combine the four collimated beams into two beams. Spatial combination of the two beams and coupling into the optical fiber is effected by use of anamorphic prisms, mirrors, and a focusing lens. The anamorphic prisms are critical elements in the NA-matching scheme, in that they reduce the fast-axis beam width to 1/6 of its original values. Inasmuch as no slow-axis beam shaping is needed, the collimating and focusing lenses are matched for 1:1 iumaging. Because these lenses are well corrected for infinite conjugates the combiner offers diffraction-limited performance along both the fast and slow axes.

  3. Manipulating coherence resonance in a quantum dot semiconductor laser via electrical pumping. (United States)

    Otto, Christian; Lingnau, Benjamin; Schöll, Eckehard; Lüdge, Kathy


    Excitability and coherence resonance are studied in a semiconductor quantum dot laser under short optical self-feedback. For low pump levels, these are observed close to a homoclinic bifurcation, which is in correspondence with earlier observations in quantum well lasers. However, for high pump levels, we find excitability close to a boundary crisis of a chaotic attractor. We demonstrate that in contrast to the homoclinic bifurcation the crisis and thus the excitable regime is highly sensitive to the pump current. The excitability threshold increases with the pump current, which permits to adjust the sensitivity of the excitable unit to noise as well as to shift the optimal noise strength, at which maximum coherence is observed. The shift adds up to more than one order of magnitude, which strongly facilitates experimental realizations.

  4. Ultrafast optical beam deflection in a pump probe configuration (United States)

    Liang, Lingliang; Tian, Jinshou; Wang, Tao; Wu, Shengli; Li, Fuli; Wang, Junfeng; Gao, Guilong


    Propagation of a signal beam in an AlGaAs/GaAs waveguide multiple-prism light deflector is theoretically investigated by solving the scalar Helmholtz equation to obtain the dependences of the temporal and spatial resolvable characteristics of the ultrafast deflector on the material dispersion of GaAs including group velocity dispersion and angular dispersion, interface reflection, and interface scattering of multiple-prism deflector. Furthermore, we experimentally confirm that, in this ultrafast beam deflection device, the deflecting angle of the signal light beam is linear with the pump fluence and the temporal resolution of the ultrafast deflection is 10 ps. Our results show that the improvement of the temporal and spatial resolvable performances is possible by properly choosing the structural parameters and enhancing the quality of the device. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274377 and 61176006) and the State Major Research Equipment Project, China (Grant No. ZDY2011-2).

  5. Time-resolved pump-probe spectroscopy of intraband absorption by a semiconductor nanorod (United States)

    Leonov, Mikhail Y.; Rukhlenko, Ivan D.; Baranov, Alexander V.; Fedorov, Anatoly V.


    We develop a theory of time-resolved pump-probe optical spectroscopy of intraband absorption of a probe pulse inside an anisotropic semiconductor nanorod. The absorption is preceded by the absorption of the pump pulse resonant to an interband transition. It is assumed that the resonantly exited states of the nanorod are interrelated via the relaxation induced by their interaction with a bath. We reveal the conditions for which the absorption of the probe's pulse is governed by a simple formula regardless of the pulse's shape. This formula is useful for the analysis of the experimental data containing information on the relaxation parameters of the nanorod's electronic subsystem.

  6. Nanoimprinted organic semiconductor laser pumped by a light-emitting diode. (United States)

    Tsiminis, Georgios; Wang, Yue; Kanibolotsky, Alexander L; Inigo, Anto R; Skabara, Peter J; Samuel, Ifor D W; Turnbull, Graham A


    An organic semiconductor laser, simply fabricated by UV-nanoimprint lithography (UV-NIL), that is pumped with a pulsed InGaN LED is demonstrated. Molecular weight optimization of the polymer gain medium on a nanoimprinted polymer distributed feedback resonator enables the lowest reported UV-NIL laser threshold density of 770 W cm(-2) , establishing the potential for scalable organic laser fabrication compatible with mass-produced LEDs.

  7. Dynamic simulation and efficiency analysis of beam pumping system

    Institute of Scientific and Technical Information of China (English)

    邢明明; 董世民; 童志雄; 田然凤; 陈慧玲


    An improved whole model of beam pumping system was built. In the detail, for surface transmission system (STS), a new mathematical model was established considering the influence of some factors on the STS’s torsional vibration, such as the time variation characteristic of equivalent stiffness of belt and equivalent rotational inertia of crank. For the sucker rod string (SRS), an improved mathematical model was built considering the influence of some parameters on the SRS’s longitudinal vibration, such as the nonlinear friction of plunger, hydraulic loss of pump and clearance leakage. The dynamic response and system efficiency of whole system were analyzed. The results show that there is a jumping phenomenon in the amplitude frequency curve, and the system.

  8. High Performance Small Optically Pumped Caesium Beam Frequency Standard

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jian-Wei; YANG Dong-Hai


    An experiment of a high performance small optically pumped caesium (Cs) beam frequency standard is reported. An extended cavity diode laser works as the probing laser, of which the frequency is stabilized by the Zeeman modulation method. The running parameters of the frequency standard are dynamically optimized via digital servo electronics. The experimental setup improves the frequency stability up to 1.8 × 10-12 atτ= 1 s and about 1.0 × 10~13 at τ= 105 s (Allan deviation).

  9. New accelerators for femtosecond beam pump-and-probe analysis

    Energy Technology Data Exchange (ETDEWEB)

    Uesaka, Mitsuru [Nuclear Engineering Research Laboratory, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan)]. E-mail:; Sakumi, Akira [Nuclear Engineering Research Laboratory, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Hosokai, Tomonao [Nuclear Engineering Research Laboratory, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Kinoshita, Kenichi [National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan); Yamaoka, Nobuaki [Nuclear Engineering Research Laboratory, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Zhidkov, Alexei [National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan); Ohkubo, Takeru [Nuclear Engineering Research Laboratory, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Ueda, Toru [Nuclear Engineering Research Laboratory, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Muroya, Yusa [Nuclear Engineering Research Laboratory, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Katsumura, Yosuke [Nuclear Engineering Research Laboratory, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Iijima, Hokuto [Japan Atomic Energy Research Institute, 2-4 Shirane, Tokai, Naka, Ibaraki 319-1195 (Japan); Tomizawa, Hiromitsu [Japan Synchrotron Radiation Research InstituteI, 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan); Kumagai, Noritaka [Japan Synchrotron Radiation Research InstituteI, 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan)


    Femtosecond electron beams are novel tool for pump-probe analysis of condensed matter. Progress in developing femtosecond electron beams with the use of both conventional accelerators and laser-plasma accelerators is discussed. In conventional accelerators, the critical issue is timing jitter and drift of the linac-laser synchronization system. Sophisticated electronic devices are developed to reduce the jitter to 330 fs (rms); the precise control of temperature at several parts of the accelerator lessens the drift to 1 ps (rms). We also report on a full-optical X-ray and e-beam system based on the laser-plasma cathode by using a 12 TW 50 fs laser, which enables 40 MeV (at maximum), 40 fs (cal.), 100 pC and quasi-monochromatic single electron bunches. Since the synchronization is done by a passive optical beam-splitter, this system intrinsically has no jitter and drift. It could achieve tens of femtoseconds time-resolved analysis in the near future.

  10. Self-similar asymptotic optical beams in semiconductor waveguides doped with quantum dots (United States)

    He, Jun-Rong; Yi, Lin; Li, Hua-Mei


    The self-similar propagation of asymptotic optical beams in semiconductor waveguides doped with quantum dots is reported. The possibility of controlling the shape of output asymptotic optical beams is demonstrated. The analytical results are confirmed by numerical simulations. We give a possible experimental protocol to generate the obtained asymptotic parabolic beams in realistic waveguides. As a generalization to the present work, the self-similar propagation of asymptotic optical beams is proposed in a power-law nonlinear medium.

  11. Design and analysis of optically pumped semiconductor VECSEL with ANECz optical control layer

    Institute of Scientific and Technical Information of China (English)

    Yuqi Zhou; Dapeng Zhao; Yajuan Li; Qingxin Yang


    Through the reversible isomerization of trans-cis-trans under the linear polarization light, the molecules of azo materials have the same tropism which is vertical to the polarization of light. This means that azo materials have photo-induced birefringence which is related to optical power and polarization angle of the light. Based on the photo-induced birefringence of azo materials, we design a new type of optically pumped semiconductor vertical external cavity surface emitting laser (OPS-VECSEL) which can control the polarization and frequency of the ejection laser. The functional molecules of azo materials are [3-azo- (4'nitro)]-(9-ethyl)-carbazole (ANECz).

  12. 2-µm Tm:Lu₂O₃ ceramic disk laser intracavity-pumped by a semiconductor disk laser. (United States)

    Saarinen, Esa J; Vasileva, Elena; Antipov, Oleg; Penttinen, Jussi-Pekka; Tavast, Miki; Leinonen, Tomi; Okhotnikov, Oleg G


    A proof-of-principle study of a 1.97-µm Tm:Lu2O3 ceramic disk laser, intracavity pumped by a 1.2-µm semiconductor disk laser, is presented. The demonstrated concept allows for improved pump absorption and takes advantage of the broad wavelength coverage provided by semiconductor disk laser technology. For thin disk lasers the small thickness of the gain element typically leads to inefficient pump light absorption. This problem is usually solved by using a complex multi-pass pump arrangement. In this study we address this challenge with a new laser concept of an intracavity pumped ceramic thin disk laser. The output power at 1.97 µm was limited to 250 mW due to heat spreader-less mounting scheme of the ceramic gain disk.

  13. Optimization of electron-beam pumped excimer laser (United States)

    Lowum, T. F.; Swecker, J. L.

    The output energy of an electron-beam pumped xenon flouride laser has been enhanced by optimizing certain electron-gun and gas-mix parameters. The optimized e-gun parameters include anode-cathode spacing, magnetic field strength, and cathode voltage. The optimized laser gas parameters include NF3 concentration, Xe concentration, and total pressure. The shortest anode-cathode spacing (9 cm), the strongest magnetic guide field (1600 Gauss), and the highest cathode voltage (375 kV) gave the highest laser output. The optimum gas concentrations were 0.05 percent NF3, 0.3 percent Xe, with Ne added to bring the total gas pressure to 60 psia. The energy degraded by 2 percent per shot with this gas mix.

  14. Improved performance of high average power semiconductor arrays for applications in diode pumped solid state lasers

    Energy Technology Data Exchange (ETDEWEB)

    Beach, R.; Emanuel, M.; Benett, W.; Freitas, B.; Ciarlo, D.; Carlson, N.; Sutton, S.; Skidmore, J.; Solarz, R.


    The average power performance capability of semiconductor diode laser arrays has improved dramatically over the past several years. These performance improvements, combined with cost reductions pursued by LLNL and others in the fabrication and packaging of diode lasers, have continued to reduce the price per average watt of laser diode radiation. Presently, we are at the point where the manufacturers of commercial high average power solid state laser systems used in material processing applications can now seriously consider the replacement of their flashlamp pumps with laser diode pump sources. Additionally, a low cost technique developed and demonstrated at LLNL for optically conditioning the output radiation of diode laser arrays has enabled a new and scalable average power diode-end-pumping architecture that can be simply implemented in diode pumped solid state laser systems (DPSSL`s). This development allows the high average power DPSSL designer to look beyond the Nd ion for the first time. Along with high average power DPSSL`s which are appropriate for material processing applications, low and intermediate average power DPSSL`s are now realizable at low enough costs to be attractive for use in many medical, electronic, and lithographic applications.

  15. Dual-pump wave mixing in semiconductor optical amplifiers: performance enhancement with long amplifiers (United States)

    Tomkos, Ioannis; Zacharopoulos, Ioannis; Syvridis, Dimitrios


    We demonstrate experimentally the improvement of the performance of the dual pump wave mixing scheme in semiconductor optical amplifiers, using long amplifier chips and high optical pump powers. The optical amplifiers used in the experiment had a ridge waveguide structure with bulk active layer and antireflective-coated angled facets. Measurements of the conversion efficiency and SBR as a function of wavelength shift are presented for a wavelength shift of more than 40 nm. The above measurements are carried out for three amplifier lengths (500 micrometers , 1000 micrometers , and 1500 micrometers ) and for different levels of the optical power of the two pumps. It will be shown that an increase in the amplifier length from 500 micrometers to 1500 micrometers results to an increase of more than 25 dB for the efficiency and more than 20 dB for the SBR. This improvement combined with the inherent advantages of the dual pump scheme (almost constant SBR and high efficiency for large wavelength shifts) results in a highly performing wavelength converter/phase conjugator, suitable for many applications.

  16. Rashba semiconductor as spin Hall material: Experimental demonstration of spin pumping in wurtzite $n$-GaN:Si



    Pure spin currents in semiconductors are essential for implementation in the next generation of spintronic elements. Heterostructures of III- nitride semiconductors are currently employed as central building-blocks for lighting and high-power devices. Moreover, the long relaxation times and the spin-orbit coupling (SOC) in these materials indicate them as privileged hosts for spin currents and related phenomena. Spin pumping is an efficient mechanism for the inception of spin current and its ...

  17. A New Pumping-Probing Scheme for the Optically Pumped Cesium Beam Frequency Standard

    Institute of Scientific and Technical Information of China (English)

    陈景标; 朱程锦; 王凤芝; 杨东海


    A new pumping-probing scheme for the optically pumped cesium beam frequency standard has been experimentally tested in our laboratory. The stability of the optically pumped cesium beam frequency standard was measured by comparing its 10 MHz output with an HP5071A commercial cesium atomic clock. The result shows that the frequency stability for the 1 s and 30000s sample times are 1.2 × 10-11 and 3.7 × 10-13, respectively. It was proved that the new pumping scheme works well.

  18. SEMICONDUCTOR TECHNOLOGY Supercritical carbon dioxide process for releasing stuck cantilever beams (United States)

    Yu, Hui; Chaoqun, Gao; Lei, Wang; Yupeng, Jing


    The multi-SCCO2 (supercritical carbon dioxide) release and dry process based on our specialized SCCO2 semiconductor process equipment is investigated and the releasing mechanism is discussed. The experiment results show that stuck cantilever beams were held up again under SCCO2 high pressure treatment and the repeatability of this process is nearly 100%.

  19. Stable, continuous-wave, intracavity, optical parametric oscillator pumped by a semiconductor disk laser (VECSEL). (United States)

    Stothard, D J M; Hopkins, J-M; Burns, D; Dunn, M H


    We report relaxation oscillation free, true continuous-wave operation of a singly-resonant, intracavity optical parametric oscillator (OPO) based upon periodically-poled, MgO-doped LiNbO3 and pumped internal to the cavity of a compact, optically-excited semiconductor disk laser (or VECSEL). The very short upper-laser-state lifetime of this laser gain medium, coupled with the enhancing effect of the high-finesse pump laser cavity in which the OPO is located, enables a low threshold, high efficiency intracavity device to be operated free of relaxation oscillations in continuous-wave mode. By optimizing for low-power operation, parametric threshold was achieved at a diode-laser power of only 1.4 W. At 8.5 W of diode-laser power, 205 mW of idler power was extracted, indicating a total down-converted power of 1.25 W, and hence a down-conversion efficiency of 83%.

  20. Pump Intensity Dependence of Two-Beam Coupling in Doped Lithium Niobate Crystals

    Institute of Scientific and Technical Information of China (English)

    Nouel Y.Kamber; XU Jing-Jun; Sonia M. Mikha; SONG Feng; ZHANG Guo-Quan; ZHANG Xin-Zheng; LIU Si-Min; ZHANG Guang-Yin


    We demonstrated experimentally the dependence of two-beam coupling on the incident pump intensity in our samples of doped LiNbO3 crystals. Our results show that there is an optimum pump intensity for the signal beam amplification, which can be easily controlled by doping the LiNbO3 crystal with suitable concentrations of Fe and damage-resistant dopants such as Mg, In, and Zn.

  1. Production of a nuclear spin polarized /sup 23/Na-beam by optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Dreves, W.; Kamke, W.; Broermann, W.; Fick, D.


    Nuclear spin polarization of an atomic /sup 23/Na-beam was produced by a combination of optical pumping with a dye laser and a sextupole magnet and alternatively, by optical pumping with two dye lasers. The maximum value measured for the vector polarization was P/sub 2/ = 0.86 +- 0.08, using beam foil spectroscopy. Further improvements of polarized ion sources based on this principle are discussed.

  2. Electron beam effects in the analysis of compound semiconductors and devices

    Energy Technology Data Exchange (ETDEWEB)

    Kazmerski, L.L.; Burnham, N.A.; Swartzlander, A.B.; Nelson, A.J.; Asher, S.E.


    The effects of electron beams on the analysis of CuInSe/sub 2/ surfaces are examined in this paper. Potential changes in the surface chemistry: including oxidation and desorption: under a range of incident probe conditions, are investigated for possible artifactual information generation. Emphasis is placed on the relationships between beam conditions and oxygen chemisorption and physisorption, since oxygen treatments of devices utilizing this semiconductor are critical to performance. Single crystals and polycrystalline thin films are analyzed and compared to establish the beam-induced phenomena.

  3. High efficiency coherent beam combining of semiconductor optical amplifiers. (United States)

    Creedon, Kevin J; Redmond, Shawn M; Smith, Gary M; Missaggia, Leo J; Connors, Michael K; Kansky, Jan E; Fan, Tso Yee; Turner, George W; Sanchez-Rubio, Antonio


    We demonstrate 40 W coherently combined output power in a single diffraction-limited beam from a one-dimensional 47-element array of angled-facet slab-coupled optical waveguide amplifiers at 1064 nm. The output from each emitter was collimated and overlapped onto a diffractive optical element combiner using a common transform lens. Phase locking was achieved via active feedback on each amplifier's drive current to maximize the power in the combined beam. The combining efficiency at all current levels was nearly constant at 87%.

  4. Effects of ion beam irradiation on semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Nashiyama, Isamu; Hirao, Toshio; Itoh, Hisayoshi; Ohshima, Takeshi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment


    Energetic heavy-ion irradiation apparatus has been developed for single-event effects (SEE) testing. We have applied three irradiation methods such as a scattered-ion irradiation method, a recoiled-atom irradiation method, and a direct-beam irradiation method to perform SEE testing efficiently. (author)

  5. A kinetic model of the electron-beam-pumped XeCl laser active medium

    Energy Technology Data Exchange (ETDEWEB)

    Boichenko, A.M.; Derzhiev, V.I.; Zhidkov, A.G.; Iakovlenko, S.I. (Institut Obshchei Fiziki, Moscow (USSR))


    Kinetic models are developed for XeCl laser active media in different buffer gases (helium, neon, and argon) pumped by an electron beam. In the calculations of the generation characteristics, allowance is made for the effect of the cavity field on the photoinduced transitions. The numerical results on the efficiency are in good agreement with experiments on electron beams. 17 refs.

  6. Production of polarized negative deuterium ion beam with dual optical pumping in KEK

    Energy Technology Data Exchange (ETDEWEB)

    Kinsho, M.; Ikegami, K.; Takagi, A. [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan); Mori, Y.


    To obtain highly nuclear-spin vector polarized negative deuterium ion beam, a dual optically pumped polarized negative deuterium ion source has been developed at KEK. It is possible to select a pure nuclear-spin state with this scheme, and negative deuterium ion beam with 100% nuclear-spin vector polarization can be produced in principle. We have obtained about 70% of nuclear-spin vector polarized negative deuterium ion beam so far. This result may open up a new possibilities for the optically pumped polarized ion source. (author)

  7. Cryogenic Semiconductor Detectors: Simulation of Signal Formation & Irradiation Beam Test

    CERN Document Server

    AUTHOR|(CDS)2091318; Stamoulis, G; Vavougios, D

    The Beam Loss Monitoring system of the Large Hadron Collider is responsible for the pro- tection of the machine from damage and for the prevention of a magnet quench. Near the interaction points of the LHC, in the triplet magnets area, the BLMs are sensitive to the collision debris, limiting their ability to distinguish beam loss signal from signal caused due to the collision products. Placing silicon & diamond detectors inside the cold mass of the mag- nets, in liquid helium temperatures, would provide significant improvement to the precision of the measurement of the energy deposition in the superconducting coil of the magnet. To further study the signal formation and the shape of the transient current pulses of the aforementioned detectors in cryogenic temperatures, a simulation application has been developed. The application provides a fast way of determining the electric field components inside the detectors bulk and then introduces an initial charge distribution based on the properties of the radiat...

  8. A Study on Photothermal Waves in a Semiconductor Material Photogenerated by a Focused Laser Beam (United States)

    Abbas, Ibrahim A.; Aly, K. A.


    In this work, the theory of coupled plasma, thermal and elastic waves were used to investigate the wave propagation on semiconductor material during photo-thermo-elastic process. A thin slim strip (TSS) medium, elastic semiconductor with isotropic and homogeneous thermal and elastic properties have been considered. The plasma, thermal and elastic waves in a TSS photo generated by a focused and intensity modulated laser beam were analyzed. Laplace transform techniques and eigenvalue approach were used to obtain the analytical solutions for carrier density, displacement, temperature, and stress. Numerical computations have been carried out on silicon-like semiconductor material. The results are presented graphically to show the effect of the coupling between the plasma, thermal, and elastic waves.

  9. Electron beam treatment of non-conducting materials by a fore-pump-pressure plasma-cathode electron beam source

    Energy Technology Data Exchange (ETDEWEB)

    Burdovitsin, V A; Klimov, A S; Medovnik, A V; Oks, E M, E-mail: burdov@fet.tusur.r [Tomsk State University of Control Systems and Radioelectronics, 634050, 40 Lenin Ave., Tomsk (Russian Federation)


    In the irradiation of an insulated target by an electron beam produced by a plasma-cathode electron beam source operating in the fore-vacuum pressure range (5-15 Pa), the target potential is much lower than the electron beam energy, offering the possibility of direct electron treatment of insulating materials. It is found that in the electron beam irradiation of a non-conducting target in a moderately high pressure range, the electron charge on the target surface is neutralized mainly by ions from a volume discharge established between the negatively charged target surface and the grounded walls of the vacuum chamber. This allows the possibility of direct electron beam treatment (heating, melting, welding) of ceramics and other non-conducting and semiconductor materials.

  10. High Photoluminescence Efficiency and Optically Pumped Lasing in Solution-Processed Mixed Halide Perovskite Semiconductors. (United States)

    Deschler, Felix; Price, Michael; Pathak, Sandeep; Klintberg, Lina E; Jarausch, David-Dominik; Higler, Ruben; Hüttner, Sven; Leijtens, Tomas; Stranks, Samuel D; Snaith, Henry J; Atatüre, Mete; Phillips, Richard T; Friend, Richard H


    The study of the photophysical properties of organic-metallic lead halide perovskites, which demonstrate excellent photovoltaic performance in devices with electron- and hole-accepting layers, helps to understand their charge photogeneration and recombination mechanism and unravels their potential for other optoelectronic applications. We report surprisingly high photoluminescence (PL) quantum efficiencies, up to 70%, in these solution-processed crystalline films. We find that photoexcitation in the pristine CH3NH3PbI3-xClx perovskite results in free charge carrier formation within 1 ps and that these free charge carriers undergo bimolecular recombination on time scales of 10s to 100s of ns. To exemplify the high luminescence yield of the CH3NH3PbI3-xClx perovskite, we construct and demonstrate the operation of an optically pumped vertical cavity laser comprising a layer of perovskite between a dielectric mirror and evaporated gold top mirrors. These long carrier lifetimes together with exceptionally high luminescence yield are unprecedented in such simply prepared inorganic semiconductors, and we note that these properties are ideally suited for photovoltaic diode operation.

  11. Diffractive Combiner of Single-Mode Pump Laser-Diode Beams (United States)

    Liu, Duncan; Wilson, Daniel; Qiu, Yueming; Forouhar, Siamak


    An optical beam combiner now under development would make it possible to use the outputs of multiple single-mode laser diodes to pump a neodymium: yttrium aluminum garnet (Nd:YAG) nonplanar ring oscillator (NPRO) laser while ensuring that the laser operates at only a single desired frequency. Heretofore, an Nd:YAG NPRO like the present one has been pumped by a single multimode laser-diode beam delivered via an optical fiber. It would be desirable to use multiple pump laser diodes to increase reliability beyond that obtainable from a single pump laser diode. However, as explained below, simplistically coupling multiple multimode laser-diode beams through a fiber-optic combiner would entail a significant reduction in coupling efficiency, and lasing would occur at one or more other frequencies in addition to the single desired frequency. Figure 1 schematically illustrates the principle of operation of a laser-diode-pumped Nd:YAG NPRO. The laser beam path is confined in a Nd:YAG crystal by means of total internal reflections on the three back facets and a partial-reflection coating on the front facet. The wavelength of the pump beam - 808 nm - is the wavelength most strongly absorbed by the Nd:YAG crystal. The crystal can lase at a wavelength of either 1,064 nm or 1,319 nm - which one depending on the optical coating on the front facet. A thermal lens effect induced by the pump beam enables stable lasing in the lowest-order transverse electromagnetic mode (the TEM00 mode). The frequency of this laser is very stable because of the mechanical stability of the laser crystal and the unidirectional nature of the lasing. The unidirectionality is a result of the combined effects of (1) a Faraday rotation induced by an externally applied magnetic field and (2) polarization associated with non-normal incidence and reflection on the front facet.

  12. Magnetic fields and the technology challenges they pose to beam-based equipment: a semiconductor perspective (United States)

    Esqueda, Vincent; Montoya, Julian A.


    As semiconductor devices shrink in size to accommodate faster processing speeds, the need for higher resolution beam-based metrology equipment and beam-based writing equipment will increase. The electron and ion beams used within these types of equipment are sensitive to very small variations in magnetic force applied to the beam. This phenomenon results from changes in Alternating Current (AC) and Direct Current (DC) magnetic flux density at the beam column which causes deflections of the beam that can impact equipment performance. Currently the most sensitive beam-based microscope manufacturers require an ambient magnetic field environment that does not have variations that exceed 0.2 milli-Gauss (mG). Studies have shown that such low levels of magnetic flux density can be extremely difficult to achieve. As examples, scissor lifts, vehicles, metal chairs, and doors moving in time and space under typical use conditions can create distortions in the Earth's magnetic field that can exceed 0.2 mG at the beam column. In addition it is known that changes in the Earth's magnetic field caused by solar flares, earthquakes, and variations in the Earth's core itself all cause changes in the magnetic field that can exceed 0.2 mG. This paper will provide the reader with the basic understanding of the emerging problem, will discuss the environmental and facility level challenges associated in meeting such stringent magnetic field environments, will discuss some of the mitigation techniques used to address the problem, and will close by discussing needs for further research in this area to assure semiconductor and nanotechnology industries are pre-positioned for even more stringent magnetic field environmental requirements.

  13. 1-kilowatt CW all-fiber laser oscillator pumped with wavelength-beam-combined diode stacks. (United States)

    Xiao, Y; Brunet, F; Kanskar, M; Faucher, M; Wetter, A; Holehouse, N


    We have demonstrated a monolithic cladding-pumped ytterbium-doped single all-fiber laser oscillator generating 1 kW of CW signal power at 1080 nm with 71% slope efficiency and near diffraction-limited beam quality. Fiber components were highly integrated on "spliceless" passive fibers to promote laser efficiency and alleviate non-linear effects. The laser was pumped through a 7:1 pump combiner with seven 200-W 91x nm fiber-pigtailed wavelength-beam-combined diode-stack modules. The signal power of such a single all-fiber laser oscillator showed no evidence of roll-over, and the highest output was limited only by available pump power.

  14. Effect of absorbed pump power on the quality of output beam from monolithic microchip lasers

    Indian Academy of Sciences (India)

    Pranab K Mukhopadhyay; K Ranganathan; Jogy George; S K Sharma; T P S Nathan


    The dependence of the beam propagation factor (2 parameter) with the absorbed pump power in the case of monolithic microchip laser under face-cooled configuration is extensively studied. Our investigations show that the 2 parameter is related to the absorbed pump power through two parameters ( and ) whose values depend on the laser material properties and laser configuration. We have shown that one parameter arises due to the oscillation of higher order modes in the microchip cavity and the other parameter accounts for the spherical aberration associated with the thermal lens induced by the pump beam. Such dependency of 2 parameter with the absorbed pump power is experimentally verified for a face-cooled monolithic microchip laser based on Nd3+ - doped GdVO4 crystal and the values of and parameters were estimated from the experimentally measured data points.

  15. ZnSe-based laser structures for electron-beam pumping with graded index waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Sorokin, S.V.; Sedova, I.V.; Ivanov, S.V. [Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, St. Petersburg 194021 (Russian Federation); Zdanova, E.V.; Zverev, M.M. [Moscow State Institute of Radio Engineering, Electronics and Automations, Moscow 117454 (Russian Federation); Gronin, S.V.


    Electron beam pumped (EBP) laser heterostructures with graded index waveguide (GIW) have been grown by molecular beam epitaxy and studied in detail. The maximum achieved output pulse power per facet is as high as 8.5 W at an electron beam energy of 16 kV. No saturation of output power with the increase of electron beam current as well as no suitable degradation of GIW EBP laser structures have been observed. The ways for further optimizations of GIW heterostructures are discussed. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Transport of electron beams and stability of optical windows in high-power e-beam-pumped krypton fluoride lasers (United States)

    Zvorykin, V. D.; Arlantsev, S. V.; Bakaev, V. G.; Rantsev, O. V.; Sergeev, P. B.; Sychugov, G. V.; Tserkovnikov, A. Yu.


    Two of the key issues of a krypton fluoride (KrF) laser driver for inertial fusion energy are the development of long life, high transparency pressure foils (to isolate vacuum in the electron beam diode from a working gas in the laser chamber), and the development of durable, stable, optical windows. Both of these problems have been studied on the single-pulse e-beam-pumped KrF laser installation GARPUN. We have measured the transport of electron beams (300 keV, 50 kA, 100 ns, 10 × 100 cm) through aluminum-beryllium and titanium foils and compared them with Monte Carlo numerical calculations. It was shown that 50-[mu]m thickness Al-Be and 20-[mu]m Ti foils had equal transmittance. However, in contrast to Ti foil, whose surface was strongly etched by fluorine, no surface modification nor fatal damages were observed for Al-Be foils after [similar]1000 laser shots and protracted fluorine exposure. We also measured the 8% reduction in the transmission of CaF2 windows under irradiation by scattered electrons when they were set at 8.5 cm apart from the e-beam-pumped region. However an applied magnetic field of [similar]0.1 T significantly reduced electron scattering both across and along the laser cell at typical pumping conditions with 1.5 atm pressure working gas. Thus the e-beam-induced absorption of laser radiation in optical windows might be fully eliminated in an e-beam-pumping scheme with magnetic field guiding.

  17. Giant narrowband twin-beam generation along the pump-energy propagation direction (United States)

    Pérez, Angela M.; Spasibko, Kirill Yu; Sharapova, Polina R.; Tikhonova, Olga V.; Leuchs, Gerd; Chekhova, Maria V.


    Walk-off effects, originating from the difference between the group and phase velocities, limit the efficiency of nonlinear optical interactions. While transverse walk-off can be eliminated by proper medium engineering, longitudinal walk-off is harder to avoid. In particular, ultrafast twin-beam generation via pulsed parametric down-conversion and four-wave mixing is only possible in short crystals or fibres. Here we show that in high-gain parametric down-conversion, one can overcome the destructive role of both effects and even turn them into useful tools for shaping the emission. In our experiment, one of the twin beams is emitted along the pump Poynting vector or its group velocity matches that of the pump. The result is markedly enhanced generation of both twin beams, with the simultaneous narrowing of angular and frequency spectrum. The effect will enable efficient generation of ultrafast twin photons and beams in cavities, waveguides and whispering-gallery mode resonators.

  18. Beam quality investigation in Nd:YAG crystal fiber amplifier pumped at >110w (United States)

    Rodin, Aleksej M.; Aleknavicius, Aidas; Michailovas, Andrejus; Dementjev, Aleksandr S.


    We present results of beam quality investigation in Nd:YAG crystal fiber amplifier seeded by ns, sub-ns and ps laser pulses counter-propagating to continuous pump of refractive index at zero stresses and zero strains is found for YAG type cubic crystals. Using plane strain approximation the analytical expression for thermal radial and tangential changes of refractive index is found, and the relation between different expressions for so-called photoelastic constants Cr,θ is established. The methods of numerical calculation of rays and Gaussian beam propagation in a graded-index medium of active element are developed. The error in widely used formula for M2 of Gaussian beam with quartic phase aberration is corrected. It is shown that beam quality degradation can be explained by active thermal lens in power amplifier when changes of transverse beam shape or beam width during amplification are taken into account.

  19. Broadband sensitive pump-probe setup for ultrafast optical switching of photonic nanostructures and semiconductors

    NARCIS (Netherlands)

    Euser, T.G.; Harding, P.J.; Vos, Willem L.


    We describe an ultrafast time resolved pump-probe spectroscopy setup aimed at studying the switching of nanophotonic structures. Both femtosecond pump and probe pulses can be independently tuned over broad frequency range between 3850 and 21 050 cm−1. A broad pump scan range allows a large optical

  20. Concept of the solar-pumped laser-photovoltaics combined system and its application to laser beam power feeding to electric vehicles (United States)

    Motohiro, Tomoyoshi; Takeda, Yasuhiko; Ito, Hiroshi; Hasegawa, Kazuo; Ikesue, Akio; Ichikawa, Tadashi; Higuchi, Kazuo; Ichiki, Akihisa; Mizuno, Shintaro; Ito, Tadashi; Yamada, Noboru; Nath Luitel, Hom; Kajino, Tsutomu; Terazawa, Hidetaka; Takimoto, Satoshi; Watanabe, Kemmei


    We have developed a compact solar-pumped laser (µSPL) employing an off-axis parabolic mirror with an aperture of 76.2 mm diameter and an yttrium aluminum garnet (YAG) ceramic rod of φ1 mm × 10 mm doped with 1% Nd and 0.1% Cr as a laser medium. The laser oscillation wavelength of 1.06 µm, just below the optical absorption edge of Si cells, is suitable for photoelectric conversion with minimal thermal loss. The concept of laser beam power feeding to an electric vehicle equipped with a photovoltaic panel on the roof was proposed by Ueda in 2010, in which the electricity generated by solar panels over the road is utilized to drive a semiconductor laser located on each traffic signal along the road. By substituting this solar-electricity-driven semiconductor laser with a solar-pumped laser, the energy loss of over 50% in converting the solar electricity to a laser beam can be eliminated. The overall feasibility of this system in an urban area such as Tokyo was investigated.

  1. Power Beaming to Space Using a Nuclear Reactor-Pumped Laser (United States)

    Lipinski, Ronald J.; Monroe, David K.; Pickard, Paul S.


    The present political and environmental climate may slow the inevitable direct utilization of nuclear power in space. In the meantime, there is another approach for using nuclear energy for space power. That approach is to let nuclear energy generate a laser beam in a ground-based nuclear reactor-pumped laser (RPL), and then beam the optical energy into space. Potential space applications for a ground-based RPL include (1) illuminating geosynchronous communication satellites in the earth's shadow to extend their lives, (2) beaming power to orbital transfer vehicles, (3) providing power (from earth) to a lunar base during the long lunar night, and (4) removing space debris. FALCON is a high-power, steady-state, nuclear reactor-pumped laser (RPL) concept which is being developed by the Department of Energy with Sandia National Laboratories as the lead laboratory. The FALCON program has experimentally demonstrated reactor-pumped lasing in various mixtures of xenon, argon, neon, and helium at wavelengths of 585, 703, 725, 1271, 1733, 1792, 2032, 2630, 2650, and 3370 nm with intrinsic efficiency as high as 2.5%. Frequency-doubling the 1733-nm line would yield a good match for photovoltaic arrays at 867 nm. Preliminary designs of an RPL suitable for power beaming have been completed. The MW- class laser is fairly simple in construction, self-powered, closed-cycle (no exhaust gases), and modular. This paper describes the FALCON program accomplishments and power-beaming applications.

  2. Spatial Combining of Laser-Diode Beams for Pumping an NPRO (United States)

    Gelsinger, Paul; Liu, Duncan; Mulder, Jerry; Aguayo, Francisco


    A free-space optical beam combiner now undergoing development makes it possible to use the outputs of multiple multimode laser diodes to pump a neodymium-doped yttrium aluminum garnet (Nd:YAG) non-planar ring oscillator (NPRO) laser while ensuring that the laser operates at only a single desired frequency. Heretofore, a Nd:YAG NPRO like the present one has been pumped by a single multimode laser-diode beam delivered via an optical fiber. It would be desirable to use multiple pump laser diodes to increase reliability beyond that obtainable from a single pump laser diode. However, as explained in this article, simplistically coupling multiple multimode laser-diode beams through a fiber-optic combiner would entail a significant reduction in coupling efficiency, and lasing would occur at one or more other frequencies in addition to the single desired frequency. To minimize coupling loss, one must ensure that the NA (approximately equal to 0.3) of the combined laser-diode beams is less than the NA of the fiber. The A(Omega) of the laser-diode beam in the slow-axis plane is 1/1.3 as large as that of the fiber. This A(Omega) is small enough to enable efficient coupling of light into the optical fiber, but too large for combining of beams in the slow-axis plane. Therefore, a pair of cylindrical lenses is used to cancel the slow-axis plane magnification introduced by the on-cylindrical lenses used to effect magnification in the fast-axis plane.

  3. Highly efficient diode-stack, end-pumped Nd:YAG slab laser with symmetrized beam quality. (United States)

    Liao, Y; Du, K; Falter, S; Zhang, J; Quade, M; Loosen, P; Poprawe, R


    An efficient high-power cw Nd:YAG slab laser, partially end pumped by diode-laser stacks, and a novel beam-shaping technique are reported. The optical efficiency amounted to 44 %, and the slope efficiency amounted to 55 %. Introducing an intracavity Brewster plate to polarize the laser beam, we obtained an optical efficiency of 35 % and a slope efficiency of 41 %. The output beam was rectangular and the beam quality asymmetric in two orthogonal directions. To equalize the beam quality, we introduced a step-mirror beam-shaping technique. The beam-shaping technique and the results obtained are discussed.

  4. Spin-exchange relaxation-free magnetometer with nearly parallel pump and probe beams (United States)

    Karaulanov, Todor; Savukov, Igor; Kim, Young Jin


    We constructed a spin-exchange relaxation-free (SERF) magnetometer with a small angle between the pump and probe beams facilitating a multi-channel design with a flat pancake cell. This configuration provides almost complete overlap of the beams in the cell, and prevents the pump beam from entering the probe detection channel. By coupling the lasers in multi-mode fibers, without an optical isolator or field modulation, we demonstrate a sensitivity of 10 f T/\\sqrt{\\text{Hz}} for frequencies between 10 Hz and 100 Hz. In addition to the experimental study of sensitivity, we present a theoretical analysis of SERF magnetometer response to magnetic fields for small-angle and parallel-beam configurations, and show that at optimal DC offset fields the magnetometer response is comparable to that in the orthogonal-beam configuration. Based on the analysis, we also derive fundamental and probe-limited sensitivities for the arbitrary non-orthogonal geometry. The expected practical and fundamental sensitivities are of the same order as those in the orthogonal geometry. We anticipate that our design will be useful for magnetoencephalography (MEG) and magnetocardiography (MCG) applications.

  5. Nonlinear effects in optical pumping of a cold and slow atomic beam

    KAUST Repository

    Porfido, N.


    By photoionizing hyperfine (HF) levels of the Cs state 62P3/2 in a slow and cold atom beam, we find how their population depends on the excitation laser power. The long time (around 180μs) spent by the slow atoms inside the resonant laser beam is large enough to enable exploration of a unique atom-light interaction regime heavily affected by time-dependent optical pumping. We demonstrate that, under such conditions, the onset of nonlinear effects in the population dynamics and optical pumping occurs at excitation laser intensities much smaller than the conventional respective saturation values. The evolution of population within the HF structure is calculated by numerical integration of the multilevel optical Bloch equations. The agreement between numerical results and experiment outcomes is excellent. All main features in the experimental findings are explained by the occurrence of “dark” and “bright” resonances leading to power-dependent branching coefficients.

  6. A study of spatial phenomena in semiconductor lasers: Beam filamentation and optical feedback effects (United States)

    Marciante, John Robert


    In an effort to improve the performance of high-power semiconductor lasers to meet the demands of applications, this thesis contains work studying the issues which limit their performance: beam filamentation and spatial feedback effects. Through computer simulations, we investigate the role of three nonlinear mechanisms which can lead to filamentation, and determine the stability boundaries of the material parameters for which the device will not exhibit filamentary tendencies. We use an analytic theory to verify these findings, and to predict the spatio- temporal nature of the filaments through an analytic expression for the gain, in which contributions of the various mechanisms can clearly be seen. We experimentally verify the spatio-temporal characteristics of the filaments, discover effects of the stripe width and transitions to chaos, and discuss how to compare the relative severity of filamentation among different devices. We propose a new method of controlling filamentation using below-bandgap semiconductor nonlinearities. With simulations, we determine under what conditions this imposed nonlinearity can counteract the carrier-induced self-focusing inside the active region. We fabricate a prototype device using new epitaxial layers containing the below-bandgap nonlinearities, and compare the performance of these new devices to a control set. In studying the spatial effects of optical feedback, we use Fresnel diffraction theory to derive an expression for the field that is reflected back into the laser. This result is applied to our computer model and used to explore the effects of feedback on narrow-stripe, broad- area, and tapered-stripe semiconductor lasers. Re- examining feedback in narrow-stripe devices through experiments and analytic theory, we investigate the coupling effects between the narrow waveguide and the feedback field, and the changes in the operating characteristics of the laser due to this coupling. We experimentally examine the beam

  7. A high-pressure He-Cd laser pumped by a nanosecond electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Goriunov, F.G.; Derzhiev, V.I.; Zhidkov, A.G.; Karelin, A.V.; Nagornyi, D.IU. (Institut Obshchei Fiziki, Moscow (USA) Institut Sil' notochnoi Elektroniki, Tomsk (USSR))


    Experimental and numerical-simulation results are presented on the stimulated emission from a high-pressure He-Cd laser pumped by a nanosecond electron beam. Consideration is given to transitions at 325, 442, 534, and 537 nm. The results of numerical calculations are in good agreement with the experimental data. It is shown that the most promising line for the production of broad-aperture high-power systems is at 442 nm. 18 refs.

  8. Fiber-based modulated optical reflectance configuration allowing for offset pump and probe beams (United States)

    Fleming, A.; Folsom, C.; Jensen, C.; Ban, H.


    A new fiber-based modulated optical reflectance configuration is developed in this work. The technique maintains the fiber-based heating laser (pump) and detection laser (probe) in close proximity at a fixed separation distance in a ceramic ferrule. The pump beam periodically heats the sample inducing thermal waves into the sample. The probe beam measures the temperature response at a known distance from the pump beam over a range of heating modulation frequencies. The thermal diffusivity of the sample may be calculated from the phase response between the input heat flux and the temperature response of a sample having a reflective surface. The unique measurement configuration is ideal for in situ measurements and has many advantages for laboratory-based systems. The design and development of the system are reported along with theoretical justification for the experimental design. The thermal diffusivities of Ge and SiC are measured and found to be within 10% of reported literature values. The diffusivity for SiO2 is measured with a relative difference of approximately 100% from the literature value when the ferrule is in contact with the sample. An additional measurement was made on the SiO2 sample with the ferrule not in contact resulting in a difference of less than 2% from the literature value. The difference in the SiO2 measurement when the ferrule is in contact with the sample is likely due to a parallel heat transfer path through the dual-fiber ferrule assembly.

  9. Optical pulling force and torques on Rayleigh semiconductor prolate and oblate spheroids in Bessel tractor beams (United States)

    Mitri, F. G.


    Optical tractor Bessel beams are gaining increased interest where a negative attractive force acting in opposite direction of wave propagation is harnessed for particle manipulation in opto-fluidics, the manufacturing of periodic composite metamaterials and other related applications. Previous works considered the spherical geometry, however, it is of some importance to develop improved models to investigate objects of more complex shapes and study the tractor beam effect on them. The aim of this work is therefore directed toward this goal, where the dipole approximation method is used to compute the optical force, spin and orbital torques on a subwavelength semiconductor spheroid illuminated by a zeroth-order Bessel vector beam. Numerical computations for the Cartesian components of the optical radiation force on prolate and oblate spheroids with arbitrary orientation are performed, with emphasis on the emergence of a negative pulling force and its dependence on the half-cone angle of the beam, the aspect ratio of the spheroid, and its orientation in space. Moreover, the Cartesian components of the spin radiation torque are computed where a negative spin torque can arise, which causes a rotational twisting effect of the spheroid around its center of mass in either the counterclockwise or the clockwise (negative) direction of spinning. In addition, the axial component of the orbital radiation torque is computed which also shows sign reversal. The results of this analysis provide a priori information for the design and development of novel optical tweezers devices and tractor beams, with potential applications in the manipulation and handling of elongated particles.

  10. Accessing thermo-mechanical properties of semiconductors using a pump-probe surface displacement method (United States)

    González-Borrero, P. P.; Lukasievicz, G. V. B.; Zanuto, V. S.; Astrath, N. G. C.; Malacarne, L. C.


    Description of the physical mechanism leading to laser induced thermal and electronic effects in semiconductors is crucial in both basic research and technological applications. In this paper, we present a thermal mirror technique to study the thermo-mechanical properties of semiconductors. A detailed theoretical investigation is presented, and the dominant effects are described in terms of the physical properties of the material. The effect of heat coupling between the sample and the surrounding fluid was taken into account and considerations on the time and spatial approximations to the photogenerated carriers profile were used to simplify the theoretical model. These approximations were then compared to numerical models and the results hold for high recombination rate semiconductors. Experiments were performed to validate the theoretical model, and the thermal diffusivity and photogenerated heat in the sample were determined. The values obtained for these properties were found to be in good agreement with literature.

  11. Continuously tunable solution-processed organic semiconductor DFB lasers pumped by laser diode

    DEFF Research Database (Denmark)

    Klinkhammer, Sönke; Liu, Xin; Huska, Klaus


    solutions on cm-scale surface gratings of different periods. We report optically pumped continuously tunable laser emission of 13 nm in the blue, 16 nm in the green and 19 nm in the red spectral region on a single chip respectively. Tuning behavior can be described with the Bragg-equation and the measured...... thickness profile. The laser threshold is low enough that inexpensive laser diodes can be used as pump sources....

  12. Laser beam shaping optical system design methods and their application in edge-emitting semiconductor laser-based LIDAR systems (United States)

    Serkan, Mert

    LIDAR (Light Detection And Ranging) systems are employed for numerous applications such as remote sensing, military applications, optical data storage, display technology, and material processing. Furthermore, they are superior to other active remote sensing tools such as RADAR systems, considering their higher accuracy and more precise resolution due to their much shorter wavelengths and narrower beamwidth. Several types of lasers can be utilized as the radiation source of several LIDAR systems. Semiconductor laser-based LIDAR systems have several advantages such as low cost, compactness, broad range of wavelengths, and high PRFs (Pulse Repetition Frequency). However, semiconductor lasers have different origins and angles of divergence in the two transverse directions, resulting in the inherent astigmatism and elliptical beam shape. Specifically, elliptical beam shape is not desirable for several laser-based applications including LIDAR systems specifically designed to operate in the far-field region. In this dissertation, two mirror-based and two lens-based beam shapers are designed to circularize, collimate, and expand an edge-emitting semiconductor laser beam to a desired beam diameter for possible application in LIDAR systems. Additionally, most laser beams including semiconductor laser beams have Gaussian irradiance distribution. For applications that require uniform illumination of an extended target area, Gaussian irradiance distribution is undesirable. Therefore, a specific beam shaper is designed to transform the irradiance distribution from Gaussian to uniform in addition to circularizing, collimating, and expanding the semiconductor laser beam. For the design of beam shapers, aperture sizes of the surfaces are preset for desired power transmission and allowed diffraction level, surface parameters of the optical components and the distances between these surfaces are determined. Design equations specific to these beam shaping optical systems are

  13. Giant Narrowband Twin-Beam Generation along the Pump Energy Propagation

    CERN Document Server

    Perez, Angela M; Sharapova, Polina R; Tikhonova, Olga V; Leuchs, Gerd; Chekhova, Maria V


    Walk-off effects, originating from the difference between the group and phase velocities, limit the efficiency of nonlinear optical interactions. While transverse walk-off can be eliminated by proper medium engineering, longitudinal walk-off is harder to avoid. In particular, ultrafast twin- beam generation via pulsed parametric down-conversion (PDC) and four-wave mixing (FWM) is only possible in short crystals or fibres or in double-path schemes. Here we show that in high-gain PDC, one can overcome the destructive role of both effects and even turn them into useful tools for shaping the emission. In our experiment, one of the twin beams is emitted along the pump Poynting vector or its group velocity matches that of the pump. The result is dramatically enhanced generation of both twin beams, with the simultaneous narrowing of angular and frequency spectrum. The effect will enable efficient generation of ultrafast twin photons and beams in cavities, waveguides, and whispering-gallery mode resonators.

  14. Towards pump-probe experiments of defect dynamics with short ion beam pulses (United States)

    Schenkel, T.; Lidia, S. M.; Weis, C. D.; Waldron, W. L.; Schwartz, J.; Minor, A. M.; Hosemann, P.; Kwan, J. W.


    A novel, induction type linear accelerator, the Neutralized Drift Compression eXperiment (NDCX-II), is currently being commissioned at Berkeley Lab. This accelerator is designed to deliver intense (up to 3 × 1011 ions/pulse), 0.6 to ∼600 ns duration pulses of 0.05-1.2 MeV lithium ions at a rate of about 2 pulses per minute onto 1-10 mm scale target areas. When focused to mm-diameter spots, the beam is predicted to volumetrically heat micrometer thick foils to temperatures of ∼30,000 °K. At lower beam power densities, the short excitation pulse with tunable intensity and time profile enables pump-probe type studies of defect dynamics in a broad range of materials. We briefly describe the accelerator concept and design, present results from beam pulse shaping experiments and discuss examples of pump-probe type studies of defect dynamics following irradiation of materials with intense, short ion beam pulses from NDCX-II.

  15. Towards pump probe experiments of defect dynamics with short ion beam pulses

    Energy Technology Data Exchange (ETDEWEB)

    Schenkel, T. [Lawrence Berkeley National Laboratory (LBNL); Lidia, S. [Lawrence Berkeley National Laboratory (LBNL); Weis, C. D. [Lawrence Berkeley National Laboratory (LBNL); Waldron, W. L. [Lawrence Berkeley National Laboratory (LBNL); Schwartz, J. [Lawrence Berkeley National Laboratory (LBNL); Minor, Andrew [Lawrence Berkeley National Laboratory (LBNL); Hosemann, P [University of California, Berkeley; Kwan, J. W. [Lawrence Berkeley National Laboratory (LBNL)


    A novel, induction type linear accelerator, the Neutralized Drift Compression eXperiment (NDCX-II), is currently being commissioned at Berkeley Lab. This accelerator is designed to deliver intense (up to 3 1011 ions/pulse), 0.6 to 600 ns duration pulses of 0.05 1.2 MeV lithium ions at a rate of about 2 pulses per minute onto 1 10 mm scale target areas. When focused to mm-diameter spots, the beam is predicted to volumetrically heat micrometer thick foils to temperatures of 30,000 K. At lower beam power densities, the short excitation pulse with tunable intensity and time profile enables pump probe type studies of defect dynamics in a broad range of materials. We briefly describe the accelerator concept and design, present results from beam pulse shaping experiments and discuss examples of pump probe type studies of defect dynamics following irradiation of materials with intense, short ion beam pulses from NDCX-II.

  16. Broadband sensitive pump-probe setup for ultrafast optical switching of photonic nanostructures and semiconductors. (United States)

    Euser, Tijmen G; Harding, Philip J; Vos, Willem L


    We describe an ultrafast time resolved pump-probe spectroscopy setup aimed at studying the switching of nanophotonic structures. Both femtosecond pump and probe pulses can be independently tuned over broad frequency range between 3850 and 21,050 cm(-1). A broad pump scan range allows a large optical penetration depth, while a broad probe scan range is crucial to study strongly photonic crystals. A new data acquisition method allows for sensitive pump-probe measurements, and corrects for fluctuations in probe intensity and pump stray light. We observe a tenfold improvement of the precision of the setup compared to laser fluctuations, allowing a measurement accuracy of better than DeltaR=0.07% in a 1 s measurement time. Demonstrations of the improved technique are presented for a bulk Si wafer, a three-dimensional Si inverse opal photonic bandgap crystal, and z-scan measurements of the two-photon absorption coefficient of Si, GaAs, and the three-photon absorption coefficient of GaP in the infrared wavelength range.

  17. In situ magnetic compensation for potassium spin-exchange relaxation-free magnetometer considering probe beam pumping effect. (United States)

    Fang, Jiancheng; Wang, Tao; Quan, Wei; Yuan, Heng; Zhang, Hong; Li, Yang; Zou, Sheng


    A novel method to compensate the residual magnetic field for an atomic magnetometer consisting of two perpendicular beams of polarizations was demonstrated in this paper. The method can realize magnetic compensation in the case where the pumping rate of the probe beam cannot be ignored. In the experiment, the probe beam is always linearly polarized, whereas, the probe beam contains a residual circular component due to the imperfection of the polarizer, which leads to the pumping effect of the probe beam. A simulation of the probe beam's optical rotation and pumping rate was demonstrated. At the optimized points, the wavelength of the probe beam was optimized to achieve the largest optical rotation. Although, there is a small circular component in the linearly polarized probe beam, the pumping rate of the probe beam was non-negligible at the optimized wavelength which if ignored would lead to inaccuracies in the magnetic field compensation. Therefore, the dynamic equation of spin evolution was solved by considering the pumping effect of the probe beam. Based on the quasi-static solution, a novel magnetic compensation method was proposed, which contains two main steps: (1) the non-pumping compensation and (2) the sequence compensation with a very specific sequence. After these two main steps, a three-axis in situ magnetic compensation was achieved. The compensation method was suitable to design closed-loop spin-exchange relaxation-free magnetometer. By a combination of the magnetic compensation and the optimization, the magnetic field sensitivity was approximately 4 fT/Hz(1/2), which was mainly dominated by the noise of the magnetic shield.

  18. Multi-gigahertz, femtosecond Airy beam optical parametric oscillator pumped at 78 MHz (United States)

    Aadhi, A.; Sharma, Varun; Chaitanya, N. Apurv; Samanta, G. K.


    We report a high power ultrafast Airy beam source producing femtosecond pulses at multi-gigahertz (GHz) repetition rate (RR). Based on intra-cavity cubic phase modulation of an optical parametric oscillator (OPO) designed in high harmonic cavity configuration synchronous to a femtosecond Yb-fiber laser operating at 78 MHz, we have produced ultrafast 2D Airy beam at multi-GHz repetition rate through the fractional increment in the cavity length. While small (Magnesium-oxide doped periodically poled LiNbO3 (MgO:PPLN) crystal for efficient generation of ultrafast Airy beam and broadband mid-IR radiation. Pumping the MgO:PPLN crystal of grating period, Λ = 30 μm and crystal temperature, T = 100 °C using a 5-W femtosecond laser centred at 1064 nm, we have produced Airy beam radiation of 684 mW in ~639 fs (transform limited) pulses at 1525 nm at a RR of ~2.5 GHz. Additionally, the source produces broadband idler radiation with maximum power of 510 mW and 94 nm bandwidth at 3548 nm in Gaussian beam profile. Using an indirect method (change in cavity length) we estimate maximum RR of the Airy beam source to be ~100 GHz. PMID:28262823

  19. Influence of total beam current on HRTEM image resolution in differentially pumped ETEM with nitrogen gas. (United States)

    Bright, A N; Yoshida, K; Tanaka, N


    Environmental transmission electron microscopy (ETEM) enables the study of catalytic and other reaction processes as they occur with Angstrom-level resolution. The microscope used is a dedicated ETEM (Titan ETEM, FEI Company) with a differential pumping vacuum system and apertures, allowing aberration corrected high-resolution transmission electron microscopy (HRTEM) imaging to be performed with gas pressures up to 20 mbar in the sample area and with significant advantages over membrane-type E-cell holders. The effect on image resolution of varying the nitrogen gas pressure, electron beam current density and total beam current were measured using information limit (Young's fringes) on a standard cross grating sample and from silicon crystal lattice imaging. As expected, increasing gas pressure causes a decrease in HRTEM image resolution. However, the total electron beam current also causes big changes in the image resolution (lower beam current giving better resolution), whereas varying the beam current density has almost no effect on resolution, a result that has not been reported previously. This behavior is seen even with zero-loss filtered imaging, which we believe shows that the drop in resolution is caused by elastic scattering at gas ions created by the incident electron beam. Suitable conditions for acquiring high resolution images in a gas environment are discussed. Lattice images at nitrogen pressures up to 16 mbar are shown, with 0.12 nm information transfer at 4 mbar.

  20. Continuously tunable solution-processed organic semiconductor DFB lasers pumped by laser diode. (United States)

    Klinkhammer, Sönke; Liu, Xin; Huska, Klaus; Shen, Yuxin; Vanderheiden, Sylvia; Valouch, Sebastian; Vannahme, Christoph; Bräse, Stefan; Mappes, Timo; Lemmer, Uli


    The fabrication and characterization of continuously tunable, solution-processed distributed feedback (DFB) lasers in the visible regime is reported. Continuous thin film thickness gradients were achieved by means of horizontal dipping of several conjugated polymer and blended small molecule solutions on cm-scale surface gratings of different periods. We report optically pumped continuously tunable laser emission of 13 nm in the blue, 16 nm in the green and 19 nm in the red spectral region on a single chip respectively. Tuning behavior can be described with the Bragg-equation and the measured thickness profile. The laser threshold is low enough that inexpensive laser diodes can be used as pump sources.

  1. Pump spot size dependent lasing threshold in organic semiconductor DFB lasers fabricated via nanograting transfer

    DEFF Research Database (Denmark)

    Liu, Xin; Klinkhammer, Sönke; Wang, Ziyao


    material. This geometrically well-defined structure allows for a systematic investigation of the laser threshold behavior. The laser thresholds for these devices show a strong dependence on the pump spot diameter. This experimental finding is in good qualitative agreement with calculations based on coupled...

  2. A Novel Contactless Method for Characterization of Semiconductors: Surface Electron Beam Induced Voltage in Scanning Electron Microscopy

    Institute of Scientific and Technical Information of China (English)

    朱世秋; E.I.RAU; 杨富华; 郑厚植


    We present a novel contactless and nondestructive method called the surface electron beam induced voltage (SEBIV) method for characterizing semiconductor materials and devices. The SEBIV method is based on the detection of the surface potential induced by electron beams of scanning electron microscopy (SEM). The core part of the SEBIV detection set-up is a circular metal detector placed above the sample surface. The capacitance between the circular detector and whole surface of the sample is estimated to be about 0.64pf. It is large enough for the detection of the induced surface potential. The irradiation mode of electron beam (e-beam) influences the signal generation. When the e-beam irradiates on the surface of semiconductors continuously, a differential signal is obtained. The real distribution of surface potentials can be obtained when a pulsed e-beam with a fixed frequency is used for irradiation and a lock-in amplifier is employed for detection. The polarity of induced potential depends on the structure of potential barriers and surface states of samples. The contrast of SEBIV images in SEM changes with irradiation time and e-beam intensity.

  3. Compact intra-cavity frequency doubled line beam green laser by a laser diode array pumped (United States)

    Yan, Boxia; Qi, Yan; Wang, Yanwei


    Compact, high power, and low-cost green laser light sources are needed in projection-related applications such as digital cinema, rear-projection television, simulators, and command and control stations. We report a LD array directly pumped intracavity SHG Nd:YVO4/PPMgLN laser without lens or waveguide in this letter. A compact 3.12 W green laser was demonstrated by intra-cavity frequency doubled using a PPMgLN bulk crystal by a 19-emitter LD array pumped(single bar), the conversion efficiency from input LD array was 9.2%. A line-beam output suitable for laser projectors was generated, which has the potential to be scalable to small volumes and low costs for laser projection displays.

  4. Integration of carbon nanotubes with semiconductor technology: fabrication of hybrid devices by III–V molecular beam epitaxy

    DEFF Research Database (Denmark)

    Stobbe, Søren; Lindelof, P. E.; Nygård, J.


    on incorporation of singlewall nanotubes in III–V semiconductor heterostructures grown by molecular beam epitaxy (MBE). We demonstrate that singlewall carbon nanotubes can be overgrown using MBE; electrical contacts to the nanotubes are obtained by GaMnAs grown at 250 °C. The resulting devices can exhibit field......We review a number of essential issues regarding the integration of carbon nanotubes in semiconductor devices for electronics: material compatibility, electrical contacts, functionalities, circuit architectures and reliability. In the second part of the paper, we present our own recent results...

  5. Green electron-beam pumped laser arrays based on II-VI nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zverev, M.M.; Gamov, N.A.; Zdanova, E.V.; Studionov, V.B.; Peregoudov, D.V. [Moscow State Inst. of Radio Engineering, Electronics and Automations, Moscow (Russian Federation); Ivanov, S.V.; Sedova, I.V.; Gronin, S.V.; Sorokin, S.V.; Kop' ev, P.S. [Ioffe Physical Technical Inst., RAS Polytekhnicheskaya, St. Petersburg (Russian Federation); Olikhov, I.M. [Gamma Co. Ltd., SRC Platan, Fryazino (Russian Federation)


    Room temperature electron-beam pumped (U = 15-26 keV) green lasers and laser arrays based on multiple quantum well II-VI structures with an extended up to 2 {mu}m waveguide have been studied. The maximum achieved output pulse power is as high as 31 and 630 W per facet from a single 0.24-mm-wide laser element at the cavity length of 0.4 mm and a laser array consisting of 26 elements, respectively. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  6. Beware the two-beam coupling phase shift: Interpreting pump-probe measurements of the nonlinear refractive index

    CERN Document Server

    Wahlstrand, J K; McCole, E T; Cheng, Y -H; Palastro, J P; Levis, R J; Milchberg, H M


    Nonlinear optics experiments measuring phase shifts induced in a weak probe pulse by a strong pump pulse must account for coherent effects that only occur when the pump and probe pulses are temporally overlapped. It is well known that a weak probe beam experiences a greater phase shift from a strong pump beam than the pump beam induces on itself. The physical mechanism behind the enhanced phase shift is diffraction of pump light into the probe direction by a nonlinear refractive index grating produced by interference between the two beams. For an instantaneous third-order response, the effect of the grating is to simply double the probe phase shift, but when delayed nonlinearities are considered, the effect is more complex. A comprehensive treatment is given for both degenerate and nondegenerate pump-probe experiments in noble and diatomic gases. Results of numerical calculations are compared to a recent transient birefringence measurement [Loriot et al., Opt. Express 17, 13429 (2009)] and a recent spectral i...

  7. Copper ion implanted aluminum nitride dilute magnetic semiconductors (DMS) prepared by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Shah, A., E-mail: [National Institute of Lasers and Optronics (NILOP), PO Nilore, Islamabad (Pakistan); DMME, Pakistan Institute of Engineering and Applied Science (PIEAS), PO Nilore, Islamabad (Pakistan); Ahmad, Jamil [DMME, Pakistan Institute of Engineering and Applied Science (PIEAS), PO Nilore, Islamabad (Pakistan); Ahmad, Ishaq [Experimental Physics Lab, National Center for Physics (NCP), Islamabad (Pakistan); Mehmood, Mazhar [DMME, Pakistan Institute of Engineering and Applied Science (PIEAS), PO Nilore, Islamabad (Pakistan); Mahmood, Arshad [National Institute of Lasers and Optronics (NILOP), PO Nilore, Islamabad (Pakistan); Rasheed, Muhammad Asim [DMME, Pakistan Institute of Engineering and Applied Science (PIEAS), PO Nilore, Islamabad (Pakistan)


    Highlights: • AlN:Cu dilute magnetic semiconductors were successfully prepared by molecular beam epitaxy followed by Cu{sup +} implantation. • Room temperature ferromagnetism was observed after annealing the samples at appropriate temperature. • XRD and Raman spectrometry excluded the possibility of formation of any secondary phases. • By doping intrinsically nonmagnetic dopants (Cu), it has been proved experimentally that their precipitates do not contribute to ferromagnetism. • The reason for ferromagnetism in Cu-doped AlN as observed was explained on the basis of p–d hybridization mechanism (Wu et al.). - Abstract: Diluted magnetic semiconductor (DMS) AlN:Cu films were fabricated by implanting Cu{sup +} ions into AlN thin films at various ion fluxes. AlN films were deposited on c-plane sapphire by molecular beam epitaxy followed by Cu{sup +} ion implantation. The structural and magnetic characterization of the samples was performed through Rutherford backscattering and channeling spectrometry (RBS/C), X-ray diffraction (XRD), Raman spectroscopy, vibrating sample magnetometer (VSM) and SQUID. Incorporation of copper into the AlN lattice was confirmed by RBS, while XRD revealed that no new phase was formed as a result of ion implantation. RBS also indicated formation of defects as a result of implantation process and the depth and degree of damage increased with an increase in ion fluence. Raman spectra showed only E{sub 2} (high) and A{sub 1} (LO) modes of wurtzite AlN crystal structure and confirmed that no secondary phases were formed. It was found that both Raman modes shift with Cu{sup +} fluences, indicating that Cu ion may go to interstitial or substitutional sites resulting in distortion or damage of lattice. Although as implanted samples showed no magnetization, annealing of the samples resulted in appearance of room temperature ferromagnetism. The saturation magnetization increased with both the annealing temperature as well as with ion

  8. Continuously tunable solution-processed organic semiconductor DFB lasers pumped by laser diode

    DEFF Research Database (Denmark)

    Klinkhammer, Sönke; Liu, Xin; Huska, Klaus


    The fabrication and characterization of continuously tunable, solution-processed distributed feedback (DFB) lasers in the visible regime is reported. Continuous thin film thickness gradients were achieved by means of horizontal dipping of several conjugated polymer and blended small molecule...... solutions on cm-scale surface gratings of different periods. We report optically pumped continuously tunable laser emission of 13 nm in the blue, 16 nm in the green and 19 nm in the red spectral region on a single chip respectively. Tuning behavior can be described with the Bragg-equation and the measured...

  9. Periodic adjustment of the position of a laser beam spot on a semiconductor saturable absorber mirror in a passively mode-locked solid-state laser

    Institute of Scientific and Technical Information of China (English)

    Xia Pa-Keti; Yan Ping; Gong Ma-Li


    A laser diode end-pumped passively mode-locked Nd:YV04 solid-state laser with a semiconductor saturable absorber mirror (SESAM),in which the intracavity laser beam spot on the SESAM can be adjusted periodically,is investigated. Inserting a rectangular prism (RP) into the laser cavity is a promising approach towards the goal of periodically moving the position of the focus spot of the intracavity pulse on the SESAM surface to avoid the long-time irradiation of the laser beam on the same position,thereby solving a series of problems caused by damage to the SESAM and greatly prolonging its usage life. The adjustment of the rectangular prism in the laser cavity does not break the stable continuous wave (CW) mode-locked condition. The laser generates a stable picosecond pulse sequence at 1064 nm with an output power of 3.6 W and a pulse width of 14 ps. The instabilities of the output power and the pulse width are 1.77% and 4.5%,respectively.

  10. PUMPS (United States)

    Thornton, J.D.


    A pump is described for conveving liquids, particure it is not advisable he apparatus. The to be submerged in the liquid to be pumped, a conduit extending from the high-velocity nozzle of the injector,and means for applying a pulsating prcesure to the surface of the liquid in the conduit, whereby the surface oscillates between positions in the conduit. During the positive half- cycle of an applied pulse liquid is forced through the high velocity nozzle or jet of the injector and operates in the manner of the well known water injector and pumps liquid from the main intake to the outlet of the injector. During the negative half-cycle of the pulse liquid flows in reverse through the jet but no reverse pumping action takes place.

  11. Effect of Electron-Beam Irradiation on Organic Semiconductor and Its Application for Transistor-Based Dosimeters. (United States)

    Kim, Jae Joon; Ha, Jun Mok; Lee, Hyeok Moo; Raza, Hamid Saeed; Park, Ji Won; Cho, Sung Oh


    The effects of electron-beam irradiation on the organic semiconductor rubrene and its application as a dosimeter was investigated. Through the measurements of photoluminescence and the ultraviolet photoelectron spectroscopy, we found that electron-beam irradiation induces n-doping of rubrene. Additionally, we fabricated rubrene thin-film transistors with pristine and irradiated rubrene, and discovered that the decrease in transistor properties originated from the irradiation of rubrene and that the threshold voltages are shifted to the opposite directions as the irradiated layers. Finally, a highly sensitive and air-stable electron dosimeter was fabricated based on a rubrene transistor.

  12. Gain and noise characteristics of a Brillouin amplifier and their dependence on the spatial structure of the pump beam

    Energy Technology Data Exchange (ETDEWEB)

    Scott, A.M.; Watkins, D.; Tapster, P. (Royal Signals and Radar Establishment, Malvern, Worcestershire WR14 3PS, UK (GB))


    Amplification of a weak input signl ({similar to}0.5 pJ) in a high-gain ({ital G}=10{sup 9}) Brillouin amplifier has resulted in an ouput signal-to-noise ratio 85:1, within a factor of 4 of the theoretical estimate. For a near-diffraction-limited Gaussian pump beam this noise increases exponentially with pump intensity with the same gain coefficients as for an input signal. When the pump beam is aberrated, the effective gain coefficient for the conjugate is enhanced by as much as a factor of 3, depending on the nature of the aberration. The enhancement factor {ital J} is found to vary significantly when the laser beam passes through different regions of the aberrator.

  13. Light-Induced Proton Pumping with a Semiconductor: Vision for Photoproton Lateral Separation and Robust Manipulation. (United States)

    Maltanava, Hanna M; Poznyak, Sergey K; Andreeva, Daria V; Quevedo, Marcela C; Bastos, Alexandre C; Tedim, João; Ferreira, Mário G S; Skorb, Ekaterina V


    Energy-transfer reactions are the key for living open systems, biological chemical networking, and the development of life-inspired nanoscale machineries. It is a challenge to find simple reliable synthetic chemical networks providing a localization of the time-dependent flux of matter. In this paper, we look to photocatalytic reaction on TiO2 from different angles, focusing on proton generation and introducing a reliable, minimal-reagent-consuming, stable inorganic light-promoted proton pump. Localized illumination was applied to a TiO2 surface in solution for reversible spatially controlled "inorganic photoproton" isometric cycling, the lateral separation of water-splitting reactions. The proton flux is pumped during the irradiation of the surface of TiO2 and dynamically maintained at the irradiated surface area in the absence of any membrane or predetermined material structure. Moreover, we spatially predetermine a transient acidic pH value on the TiO2 surface in the irradiated area with the feedback-driven generation of a base as deactivator. Importantly we describe how to effectively monitor the spatial localization of the process by the in situ scanning ion-selective electrode technique (SIET) measurements for pH and the scanning vibrating electrode technique (SVET) for local photoelectrochemical studies without additional pH-sensitive dye markers. This work shows the great potential for time- and space-resolved water-splitting reactions for following the investigation of pH-stimulated processes in open systems with their flexible localization on a surface.

  14. Accurate determination of electronic transport properties of silicon wafers by nonlinear photocarrier radiometry with multiple pump beam sizes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qian [Institute of Optics and Electronics, Chinese Academy of Sciences, P. O. Box 350, Shuangliu, Chengdu 610209 (China); University of the Chinese Academy of Sciences, Beijing 100039 (China); Li, Bincheng, E-mail: [Institute of Optics and Electronics, Chinese Academy of Sciences, P. O. Box 350, Shuangliu, Chengdu 610209 (China); School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China)


    In this paper, photocarrier radiometry (PCR) technique with multiple pump beam sizes is employed to determine simultaneously the electronic transport parameters (the carrier lifetime, the carrier diffusion coefficient, and the front surface recombination velocity) of silicon wafers. By employing the multiple pump beam sizes, the influence of instrumental frequency response on the multi-parameter estimation is totally eliminated. A nonlinear PCR model is developed to interpret the PCR signal. Theoretical simulations are performed to investigate the uncertainties of the estimated parameter values by investigating the dependence of a mean square variance on the corresponding transport parameters and compared to that obtained by the conventional frequency-scan method, in which only the frequency dependences of the PCR amplitude and phase are recorded at single pump beam size. Simulation results show that the proposed multiple-pump-beam-size method can improve significantly the accuracy of the determination of the electronic transport parameters. Comparative experiments with a p-type silicon wafer with resistivity 0.1–0.2 Ω·cm are performed, and the electronic transport properties are determined simultaneously. The estimated uncertainties of the carrier lifetime, diffusion coefficient, and front surface recombination velocity are approximately ±10.7%, ±8.6%, and ±35.4% by the proposed multiple-pump-beam-size method, which is much improved than ±15.9%, ±29.1%, and >±50% by the conventional frequency-scan method. The transport parameters determined by the proposed multiple-pump-beam-size PCR method are in good agreement with that obtained by a steady-state PCR imaging technique.

  15. A Passively Mode-Locked Diode-End-Pumped Nd:YAG Laser with a Semiconductor Saturable Absorber Mirror Grown by Metal Organic Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    王勇刚; 马骁宇; 李春勇; 张治国; 张丙元; 张志刚


    We report the experimental results of a mode-locked diode-end-pumped Nd:YAG laser with a semiconductor saturable absorber mirror(SESAM)from which we achieved a 10ps pulse duration at 150MHz repetition rate.The SESAM was grown by metal organic chemical vapour deposition at low temperature.The recovery time was measured to be 0.5 ps,indicating the potential pulse compression to sub-picoseconds.

  16. Ion beam synthesis and characterization of metastable group-IV alloy semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Naoto; Hasegawa, Masataka; Hayashi, Nobuyuki; Makita, Yunosuke; Shibata, Hajime [Electrotechnical Lab., Tsukuba, Ibaraki (Japan); Katsumata, Hiroshi; Uekusa, Shin-ichiro


    New Group-IV metastable alloy semiconductors and their heterostructures based on combinations of C-Si-Ge-Sn are recently attracting interest because of feasible new electronic and optoelectronic application in Si-technology and here research works on synthesis and characterization of the epitaxial heterostructures of Si-C, Si-Sn on Si fabricated by ion implantation together either with ion-beam-induced epitaxial crystallization (IBIEC) or solid phase epitaxial growth (SPEG) have been investigated. Formations of layers of Si{sub 1-y}C{sub y} (y=0.014 at peak concentration) on Si(100) have been performed by high-dose implantation of 17 keV C ions and successive IBIEC with 400 keV Ar or Ge ion bombardments at 300-400degC or SPEG up to 750degC. Crystalline growth by IBIEC has shown a lower growth rate in Si{sub 1-y}C{sub y}/Si than in intrinsic Si due mainly to the strain existence, which was observed by the X-ray diffraction (XRD) measurements. Photoluminescence(PL) measurements have revealed I{sub 1} or G line emissions that are relevant to small vacancy clusters or C pair formation, respectively. The crystalline growth of Si{sub 1-z}Sn{sub z} layers by 110 keV {sup 120}Sn ion implantation (z=0.029 and z=0.058 at peak concentration) into Si(100) followed either by IBIEC or by SPEG has been also investigated. PL emission from both IBIEC-grown and SPEG-grown samples with the lower Sn concentration has shown similar peaks to those by ion-implanted and annealed Si samples with intense I{sub 1} or I{sub 1}-related (Ar) peaks. Present results suggest that IBIEC has a feature for the non-thermal equilibrium fabrication of Si-C and Si-Sn alloy semiconductors. (J.P.N.)

  17. Application of Metal-Semiconductor-Metal (MSM) Photodetectors for Transverse and Longitudinal Intra-Bunch Beam Diagnostics

    CERN Document Server

    Steinhagen, R J; Boland, M J; Lucas, T G; Rassool, R P


    The performance reach of modern accelerators is often governed by the ability to reliably measure and control the beam stability. In high-brightness lepton and high-energy hadron accelerators, the use of optical diagnostic techniques is becoming more widespread as the required bandwidth, resolution and high RF beam power level involved limit the use of traditional electro-magnetic RF pick-up based methods. This contribution discusses the use of fibre-coupled ultra-fast Metal-Semiconductor-Metal Photodetectors (MSM-PD) as an alternative, dependablemeans to measure signals derived from electro-optical and synchrotron-light based diagnostics systems. It describes the beam studies performed at CERN’s CLIC Test Facility (CTF3) and the Australian Synchrotron to assess the feasibility of this technology as a robust, wide-band and sensitive technique for measuring transverse intra-bunch and bunch-by-bunch beam oscillations, longitudinal beam profiles, un-bunched beam population and beam-halo profiles. The amplifica...

  18. Electron beam pumped III-V nitride vertical cavity surface emitting lasers grown by molecular beam epitaxy (United States)

    Ng, Hock Min

    The design and fabrication by molecular beam epitaxy of a prototype vertical cavity laser based on the III-V nitrides were investigated in this work. The bottom mirror of the laser consists of distributed Bragg reflectors (DBRs) based on quarterwave AlN (or AlxGa1-xN) and GaN layers. Such DBRs were designed for maximum reflectivity in the spectral region from 390--600 nm. The epitaxial growth of these two binaries on each other revealed that while AlN grows on GaN in a two-dimensional mode (Frank-van der Merwe mode), GaN grows on AlN in a three-dimensional mode (Stranski-Krastanov mode). In spite of that, DBRs with peak reflectance up to 99% and bandwidths of 45nm were fabricated. The measured reflectance spectra were compared with simulations using the transmission matrix method. The mechanical stability of these DBR structures due to non-uniform distribution of strain arising from lattice or thermal mismatch of the various components were also addressed. The active region of the laser consists of InGaN/GaN multiple quantum wells (MQWs). The existence of up to the third order diffraction peaks in the x-ray diffraction spectra suggests that the interfaces between InGaN and GaN are sharp with little interdiffusion at the growth temperature. The photoluminescence and cathodoluminescence spectra were analyzed to determine the optical quality of the MQWs. The best MQWs were shown to have a single emission peak at 397nm with full width half maximum (FWHM) of 11nm. Cathodoluminescence studies showed that there are spatially localized areas of intense light emission. The complete device was formed on (0001) sapphire substrates using the previously described DBRs as bottom mirrors and the MQWs as the active region. The top mirror of the device consists of metallic silver. The device was pumped by an electron beam from the top mirror side and the light output was collected from the sapphire side. Measurements at 100K showed narrowing of the linewidth with increasing pump

  19. Directly solar-pumped iodine laser for beamed power transmission in space (United States)

    Choi, S. H.; Meador, W. E.; Lee, J. H.


    A new approach for development of a 50-kW directly solar-pumped iodine laser (DSPIL) system as a space-based power station was made using a confocal unstable resonator (CUR). The CUR-based DSPIL has advantages, such as performance enhancement, reduction of total mass, and simplicity which alleviates the complexities inherent in the previous system, master oscillator/power amplifier (MOPA) configurations. In this design, a single CUR-based DSPIL with 50-kW output power was defined and compared to the MOPA-based DSPIL. Integration of multiple modules for power requirements more than 50-kW is physically and structurally a sound approach as compared to building a single large system. An integrated system of multiple modules can respond to various mission power requirements by combining and aiming the coherent beams at the user's receiver.

  20. One-color one-beam pumping of Er(3+)-doped ZBLAN glasses for a three-dimensional two-step excitation display. (United States)

    Honda, T; Doumuki, T; Akella, A; Galambos, L; Hesselink, L


    We demonstrate a one-color one-beam pumping method for a three-dimensional two-step excitation fluorescent display with Er(3+) -doped ZBLAN glass. A localized green fluorescent spot is obtained by use of a focused pump-light beam at 979 nm. The quantum efficiency of the two-step excitation fluorescence is investigated in a time-dependent analysis and an experiment with a pulsed pump light.

  1. Two-photon absorption coefficient dichroism in Ⅱ-Ⅵ semiconductor crystals

    Institute of Scientific and Technical Information of China (English)

    Ma Guo-Hong; Ma Hong-Liang; Tang Sing-Hai


    Considering two beams propagate in semiconductor crystal, this paper discusses the polarization dependence of pump beam-induced intensity attenuation of probe beam due to two-photon absorption (TPA). Numerical calculation and experimental measurement demonstrate that TPA coefficient is polarization dependent. For homogeneous materials,probe beam attenuation arises from the imaginary part of diagonal and off-diagonal components of third-order nonlinear susceptibilities.

  2. Two-beam combined 3.36  J, 100  Hz diode-pumped high beam quality Nd:YAG laser system. (United States)

    Qiu, J S; Tang, X X; Fan, Z W; Wang, H C; Liu, H


    In this paper, we develop a diode-pumped all-solid-state high-energy and high beam quality Nd:YAG laser system. A master oscillator power amplifier structure is used to provide a high pulse energy laser output with a high repetition rate. In order to decrease the amplifier working current so as to reduce the impact of the thermal effect on the beam quality, a beam splitting-amplifying-combining scheme is adopted. The energy extraction efficiency of the laser system is 50.68%. We achieve 3.36 J pulse energy at a 100 Hz repetition rate with a pulse duration of 7.1 ns, a far-field beam spot 1.71 times the diffraction limit, and 1.07% energy stability (RMS).

  3. A split-beam probe-pump-probe scheme for femtosecond time resolved protein X-ray crystallography

    Directory of Open Access Journals (Sweden)

    Jasper J. van Thor


    Full Text Available In order to exploit the femtosecond pulse duration of X-ray Free-Electron Lasers (XFEL operating in the hard X-ray regime for ultrafast time-resolved protein crystallography experiments, critical parameters that determine the crystallographic signal-to-noise (I/σI must be addressed. For single-crystal studies under low absorbed dose conditions, it has been shown that the intrinsic pulse intensity stability as well as mode structure and jitter of this structure, significantly affect the crystallographic signal-to-noise. Here, geometrical parameters are theoretically explored for a three-beam scheme: X-ray probe, optical pump, X-ray probe (or “probe-pump-probe” which will allow experimental determination of the photo-induced structure factor amplitude differences, ΔF, in a ratiometric manner, thereby internally referencing the intensity noise of the XFEL source. In addition to a non-collinear split-beam geometry which separates un-pumped and pumped diffraction patterns on an area detector, applying an additional convergence angle to both beams by focusing leads to integration over mosaic blocks in the case of well-ordered stationary protein crystals. Ray-tracing X-ray diffraction simulations are performed for an example using photoactive yellow protein crystals in order to explore the geometrical design parameters which would be needed. The specifications for an X-ray split and delay instrument that implements both an offset angle and focused beams are discussed, for implementation of a probe-pump-probe scheme at the European XFEL. We discuss possible extension of single crystal studies to serial femtosecond crystallography, particularly in view of the expected X-ray damage and ablation due to the first probe pulse.

  4. Multi-frequency inversion-charge pumping for charge separation and mobility analysis in high-k/InGaAs metal-oxide-semiconductor field-effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Djara, V.; Cherkaoui, K.; Negara, M. A.; Hurley, P. K., E-mail: [Tyndall National Institute, University College Cork, Dyke Parade, Cork (Ireland)


    An alternative multi-frequency inversion-charge pumping (MFICP) technique was developed to directly separate the inversion charge density (N{sub inv}) from the trapped charge density in high-k/InGaAs metal-oxide-semiconductor field-effect transistors (MOSFETs). This approach relies on the fitting of the frequency response of border traps, obtained from inversion-charge pumping measurements performed over a wide range of frequencies at room temperature on a single MOSFET, using a modified charge trapping model. The obtained model yielded the capture time constant and density of border traps located at energy levels aligned with the InGaAs conduction band. Moreover, the combination of MFICP and pulsed I{sub d}-V{sub g} measurements enabled an accurate effective mobility vs N{sub inv} extraction and analysis. The data obtained using the MFICP approach are consistent with the most recent reports on high-k/InGaAs.

  5. Measurements of nonlinear lensing in a semiconductor disk laser gain sample under optical pumping and using a resonant femtosecond probe laser (United States)

    Quarterman, A. H.; Mirkhanov, S.; Smyth, C. J. C.; Wilcox, K. G.


    Accurate characterizations of the nonlinear refractive index of semiconductor disk laser (SDL) gain samples are of critical importance for understanding the behavior of self-mode-locked SDLs. Here we describe measurements of nonlinear lensing in an SDL gain sample for a wide range of optical pump intensities and using a probe which is on resonance with the quantum wells in the SDL gain sample and whose intensity, pulse duration, and spot size are chosen to be similar to those reported in self-mode-locked SDLs. Under these conditions, we determine an effective value of the nonlinear refractive index, n2 = -6.5 × 10-13 cm2/W at zero pump intensity, and find that the value of n2 changes by less than 25% over the range of pump intensities studied. The nonlinear refractive index is measured using a variation on the well-established z-scan technique, which was modified to make it better suited to the measurement of optically pumped samples.

  6. Epitaxial growth of dilute nitride-arsenide compound semiconductors by molecular beam epitaxy (United States)

    Adamcyk, Martin

    InyGa1-yAs 1-xNx containing a small amount of nitrogen (x narrow bandgap semiconductor alloy that has advantageous properties for the fabrication of optoelectronic devices. In this thesis, we seek to improve the material quality of InGaAsN and GaAsN by studying how the epitaxial growth conditions affect both the structural and electronic properties of the alloy. We describe a novel RF plasma source based on a helical resonator design that was developed for the incorporation of nitrogen into GaAsN and InGaAsN thin films grown by molecular beam epitaxy. The plasma source is equipped with a baffle apparatus that decreases the ion content of the flux. We show how the structural and electronic properties of InGaAsN epilayers depend on the growth conditions. In situ light scattering measurements and atomic force microscopy show that a faceted surface morphology occurs when growth conditions increase adatom surface diffusion: slow growth rate, high substrate temperature and high V/III ratio. Large nitrogen concentrations also favour the faceted growth mode. The residual strain in relaxed InGaAsN films is found to be higher than in InGaAs epilayers having the same lattice mismatch. In situ substrate curvature measurements were used to monitor the strain state of the sample in real time during the growth. Ex situ transmission electron microscopy and x-ray diffraction measurements agree with the residual strain determined with the in situ monitor. These characterization results also indicate that threading dislocation glide is slower in InGaAsN than in InGaAs. Finally, we find that the electronic properties of InGaAsN are generally degraded with increasing nitrogen content. However, by choosing appropriate growth conditions, we demonstrate InGaAsN quantum wells with room temperature photoluminescence efficiencies that are comparable to InGaAs structures. These photoluminescence results may be related to the faceting transition that was observed during GaAsN growth. In

  7. Phase locking of two beams emitting from a side pumped Nd:YAG slab with self-imaging resonator

    Institute of Scientific and Technical Information of China (English)

    Qianjin Tang; Yongai Yu; Qiquan Hu


    Intracavity phase locking of two beams emitting from a block of Nd:YAG medium side-pumped by laser diode array (LDA) was investigated experimentally. The interference fringes of the two beams occured at the output mirror. The coherent output power of 1.13 W was obtained with combination efficiency of 64.9% and coherence degree of about 60%. Only a metallic wire as a filter located at a suitable position close to the output mirror can efficiently lock the entire structure with less than 8% power loss.

  8. A measurement of the absolute neutron beam polarization produced by an optically pumped sup 3 He neutron spin filter

    CERN Document Server

    Rich, D R; Crawford, B E; Delheij, P P J; Espy, M A; Haseyama, T; Jones, G; Keith, C D; Knudson, J; Leuschner, M B; Masaike, A; Masuda, Y; Matsuda, Y; Penttilae, S I; Pomeroy, V R; Smith, D A; Snow, W M; Szymanski, J J; Stephenson, S L; Thompson, A K; Yuan, V


    The capability of performing accurate absolute measurements of neutron beam polarization opens a number of exciting opportunities in fundamental neutron physics and in neutron scattering. At the LANSCE pulsed neutron source we have measured the neutron beam polarization with an absolute accuracy of 0.3% in the neutron energy range from 40 meV to 10 eV using an optically pumped polarized sup 3 He spin filter and a relative transmission measurement technique. sup 3 He was polarized using the Rb spin-exchange method. We describe the measurement technique, present our results, and discuss some of the systematic effects associated with the method.

  9. Temperature-Induced Wavelength Shift of Electron-Beam-Pumped Lasers from CdSe, CdS, and ZnO

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher


    Experimental results on the temperature dependence of the laser frequency and threshold pump power are presented in the range from liquid helium to room temperature for electron-beam-pumped CdSe, CdS, and ZnO lasers. A linear shift of the laser frequency at high temperatures and a relatively slow...

  10. Ion beam sputtered nanostructured semiconductor surfaces as templates for nanomagnet arrays

    Energy Technology Data Exchange (ETDEWEB)

    Teichert, C [Institute of Physics, University of Leoben, 8700 Leoben (Austria); De Miguel, J J [Department of Condensed Matter Physics, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Bobek, T [Institute of Semiconductor Technology, University of Aachen, 52074 Aachen (Germany)], E-mail:


    The ongoing tendency for increasing the storage densities in magnetic recording techniques requires a search for efficient routes to fabricate and characterize nanomagnet arrays on solid supports. Spontaneous pattern formation in semiconductor heteroepitaxy or under ion erosion of semiconductor surfaces yields nanostructured substrates that can serve as templates for subsequent deposition of magnetic material. The nanostructured morphology of the template can easily be replicated into the magnetic coating by means of the shadow deposition technique which allows one to selectively cover specific areas of the template with magnetic material. Here, we demonstrate that ion bombardment induced hexagonally arranged GaSb dots are suitable templates for fabricating by shadow deposition close-packed nanomagnets with a lateral extension of {<=}50 nm, i.e. with a resulting storage density of up to 0.2 Tbit in{sup -2}. Magnetic-force microscopy (MFM) measurements revealed that the individual nanomagnets-which are located on the tops of the semiconductor hillocks-are single domain and show mainly independent magnetization. The coupling behaviour was estimated from correlation function analysis of the MFM data. In addition, magneto-optical Kerr effect measurements demonstrate that the nanomagnets can be magnetized either out-of-plane or in-plane and show remanence at room temperature, with a coercive field of 120 mT.

  11. Pump beam waist-dependent pulse energy generation in Nd:YAG/Cr4+:YAG passively Q-switched microchip laser (United States)

    Li, Chao-yu; Dong, Jun


    The incident pump beam waist-dependent pulse energy generation in Nd:YAG/Cr4+:YAG composite crystal passively Q-switched microchip laser has been investigated experimentally and theoretically by moving the Nd:YAG/Cr4+:YAG composite crystal along the pump beam direction. Highest pulse energy of 0.4 mJ has been generated when the Nd:YAG/Cr4+:YAG composite crystal is moved about 6 mm away from the focused pump beam waist. Laser pulses with pulse width of 1.7 ns and peak power of over 235 kW have been achieved. The theoretically calculated effective laser beam area at different positions of Nd:YAG/Cr4+:YAG composite crystal along the pump beam direction is in good agreement with the experimental results. The highest peak power can be generated by adjusting the pump beam waist incident on the Nd:YAG/Cr4+:YAG composite crystal to optimize the effective laser beam area in passively Q-switched microchip laser.

  12. Spontaneous Generation of Vortex Array Beams from a Thin-Slice Solid-State Laser with Wide-Aperture Laser-Diode Pumping

    CERN Document Server

    Otsuka, Kenju


    We studied complex lasing pattern formations in a thin-slice solid-state laser with wide-aperture laser-diode end-pumping. Radial and rectangular vortex arrays were found to be formed in a controlled fashion with symmetric and asymmetric pump beam profiles, respectively. Most of these vortices exhibited single-frequency oscillations arising from a spontaneous process of transverse mode locking of nearly degenerate modes assisted by the laser nonlinearity. Single-frequency rectangular array beams consisting of a large number of vortices, e.g., closely packed 36 or 46 vortex pixels, were generated, originating from Ince-Gaussian modes excited by the asymmetric pumping.

  13. Cavity-induced phase stability to decelerate a fast molecular beam via feedback-controlled time-varying optical pumps

    CERN Document Server

    Lan, Zhihao


    We have identified a novel phase stability mechanism from the intracavity field-induced self-organization of a fast-moving molecular beam into travelling molecular packets in the bad cavity regime, which is then used to decelerate the molecular packets by feedback-controlled time-varying laser pumps to the cavity. We first applied the linear stability analysis to derive an expression for this self-organization in the adiabatic limit and show that the self-organization of the beam leads to the formation of travelling molecular packets, which in turn function as a dynamic Bragg grating, thus modulating periodically the intracavity field by superradiant scattering of the pump photons. The modulation encodes the position information of the molecular packets into the output of the intracavity field instantaneously. We then applied time-varying laser pumps that are automatically switched by the output of the intracavity field to slow down the molecular packets via a feedback mechanism and found that most of the mol...

  14. Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures. (United States)

    Chen, Ruei-San; Tang, Chih-Che; Shen, Wei-Chu; Huang, Ying-Sheng


    Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor performance, which suggest a new direction for the development of next-generation ultrathin and flexible photonic and electronic devices. Enhanced luminescence quantum efficiency has been widely observed in these atomically thin 2D crystals. However, dimension effects beyond quantum confinement thicknesses or even at the micrometer scale are not expected and have rarely been observed. In this study, molybdenum diselenide (MoSe2) layer crystals with a thickness range of 6-2,700 nm were fabricated as two- or four-terminal devices. Ohmic contact formation was successfully achieved by the focused-ion beam (FIB) deposition method using platinum (Pt) as a contact metal. Layer crystals with various thicknesses were prepared through simple mechanical exfoliation by using dicing tape. Current-voltage curve measurements were performed to determine the conductivity value of the layer nanocrystals. In addition, high-resolution transmission electron microscopy, selected-area electron diffractometry, and energy-dispersive X-ray spectroscopy were used to characterize the interface of the metal-semiconductor contact of the FIB-fabricated MoSe2 devices. After applying the approaches, the substantial thickness-dependent electrical conductivity in a wide thickness range for the MoSe2-layer semiconductor was observed. The conductivity increased by over two orders of magnitude from 4.6 to 1,500 Ω(-) (1) cm(-) (1), with a decrease in the thickness from 2,700 to 6 nm. In addition, the temperature-dependent conductivity indicated that the thin MoSe2 multilayers exhibited considerably weak semiconducting behavior with activation energies of 3.5-8.5 meV, which are considerably smaller than those (36-38 meV) of the bulk. Probable surface-dominant transport properties and the presence of a high surface electron concentration in MoSe2 are proposed

  15. Optimization of beam quality and optical-to-optical efficiency of Yb:YAG thin-disk regenerative amplifier by pulsed pumping. (United States)

    Chyla, Michal; Miura, Taisuke; Smrz, Martin; Jelinkova, Helena; Endo, Akira; Mocek, Tomas


    We demonstrate an optimization method of beam quality and optical-to-optical (O-O) efficiency by using pulsed pumping. By changing the pulse duration and the peak intensity of pump pulse at the repetition rate of 1 kHz, the beam quality and O-O efficiency of the Yb:YAG thin-disk regenerative amplifier can be improved. We applied this method to the regenerative amplifier under the pumping wavelength of both 940 and 969 nm, and found that the method was effective in both pumping wavelengths. Although a Yb:YAG thin disk soldered on a copper tungsten heat sink, which has poor thermal properties compared with a thin disk mounted on a diamond substrate, was applied as a gain media, we obtained 45 mJ output with 19.3% O-O efficiency and nearly diffraction-limited beam.

  16. ’Molecular Beam Epitaxial Growth, Characterization, and Devices of Modulated Semiconductor Structures’ (United States)


    on reverse if necessary and identify by block number) Key Words: Molecular Beam Epitaxv, X-ray diffraction, RHEED, GeSn , AlGaSb, Surface Structure so far has been used in the study of metastable GeSn alloys grown on InP and GaSb substrates, and in analysis of the (Al, Ga)Sb material system...Homma, "Molecular beam epitaxial 6 growth of metastable GeSn alloys", Sept. 13-15, 1989, North Carolina State University, Raleigh, N.C. Also to be

  17. Semiconductor cluster beams: One and two color ionization studies of Six and Gex


    Heath, J R; Liu, Yuan; O'Brien, S. C.; Zhang, Qing-ling; Curl, R. F.; Tittel, F.K.; Smalley, R.E.


    Supersonic beams of clusters of Si and Ge atoms have been produced by laser vaporization followed by supersonic expansion in a helium carrier. The cluster beams were characterized by F2(7.9 eV) and ArF(6.4 eV) excimer laser ionization accompanied by time-of-flight mass analysis. In addition, the feasibility of a resonant two-photon ionization (R2PI) spectroscopic study was explored by two-color experiments involving initial excitation with the second (2.36 eV) and third (3.54 eV) harmonics of...

  18. Dry vacuum pumps (United States)

    Sibuet, R.


    For decades and for ultimate pressure below 1 mbar, oil-sealed Rotary Vane Pumps have been the most popular solution for a wide range of vacuum applications. In the late 80ies, Semiconductor Industry has initiated the development of the first dry roughing pumps. Today SC applications are only using dry pumps and dry pumping packages. Since that time, pumps manufacturers have developed dry vacuum pumps technologies in order to make them attractive for other applications. The trend to replace lubricated pumps by dry pumps is now spreading over many other market segments. For the Semiconductor Industry, it has been quite easy to understand the benefits of dry pumps, in terms of Cost of Ownership, process contamination and up-time. In this paper, Technology of Dry pumps, its application in R&D/industries, merits over conventional pumps and future growth scope will be discussed.

  19. Comparative studies of semiconductor saturable absorber mirror mode-locking dynamics in pulsed diode-end-pumped picosecond Nd:GdVO4 and Nd:YAG lasers

    Institute of Scientific and Technical Information of China (English)

    Bingyuan Zhang; Gang Li; Meng Chen; Guoju Wang; Yonggang Wang


    Ultrashort pulses were generated in passively mode-locked Nd:YAG and Nd:GdVO4 lasers pumped by a pulsed laser diode with 10-Hz repetition rate. Stable mode-locked pulse trains were produced with the pulse width of 10 ps. The evolution of the mode-locked pulse was observed in the experiment and was discussed in detail. Comparing the pulse evolutions of Nd:YAG and Nd:GdVO4 lasers, we found that the buildup time of the steady-state mode-locking with semiconductor saturable absorber mirrors (SESAMs) was relevant to the upper-state lifetime and the emission cross-section of the gain medium.

  20. Heterodyne pump-probe and four-wave mixing in semiconductor optical amplifiers using balanced lock-in detection

    DEFF Research Database (Denmark)

    Borri, Paola; Langbein, Wolfgang; Mørk, Jesper;


    We demonstrate a new detection scheme for pump-probe and four-wave mixing heterodyne experiments, using balanced detection and a dual-phase lock-in for spectral filtering. The technique allows the use of low repetition-rate laser systems, as is demonstrated on an InGaAsP/InP bulk optical amplifier...... at 1.53 mym. Ultrafast pump-induced changes in the amplitude and phase of the transmitted probe signal are simultaneously measured, going from small to large signal changes and with no need of an absolute phase calibration, showing the versatility and the sensitivity of this detection scheme....... The results for small perturbations are consistent with previous pump-probe experiments reported in literature. Time-resolved four-wave mixing in the absorption regime of the device is measured, and compared with numerical simulations, indicating a 100 fs dephasing time....

  1. He-Cd lasers operating at wavelengths of 442, 534, and 538 nm and pumped by a nanosecond electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Derzhiev, V.I.; Zhidkov, A.G.; Karelin, A.V.; Nagornyi, D.IU.; Skakun, V.S.


    Effective lasing was obtained with an He-Cd laser in blue (442 nm) and green (534 and 538 nm) under nanosecond-electron-beam pumping. The dependence of the lasing characteristics on gas temperature and cold-helium pressure is examined along with the time characteristics of lasing. The maximum power was 200 W for the blue line and 400 W for the green lines; the efficiency with respect to energy injected into the active region was 0.1 percent. 6 references.

  2. Accelerator-based electron beam technologies for modification of bipolar semiconductor devices (United States)

    Pavlov, Y. S.; Surma, A. M.; Lagov, P. B.; Fomenko, Y. L.; Geifman, E. M.


    Radiation processing technologies for static and dynamic parameters modification of silicon bipolar semiconductor devices implemented. Devices of different classes with wide range of operating currents (from a few mA to tens kA) and voltages (from a few volts to 8 kV) were processed in large scale including power diodes and thyristors, high-frequency bipolar and IGBT transistors, fast recovery diodes, pulsed switching diodes, precise temperature- compensated Zener diodes (in general more than fifty 50 device types), produced by different enterprises. The necessary changes in electrical parameters and characteristics of devices caused by formation in the device structures of electrically active and stable in the operating temperature range sub-nanoscale recombination centres. Technologies implemented in the air with high efficiency and controllability, and are an alternative to diffusion doping of Au or Pt, γ-ray, proton and low-Z ion irradiation.

  3. Pump-probe imaging of the fs-ps-ns dynamics during femtosecond laser Bessel beam drilling in PMMA. (United States)

    Yu, Yanwu; Jiang, Lan; Cao, Qiang; Xia, Bo; Wang, Qingsong; Lu, Yongfeng


    A pump-probe shadowgraph imaging technique was used to reveal the femtosecond-picosecond-nanosecond multitimescale fundamentals of high-quality, high-aspect-ratio (up to 287:1) microhole drilling in poly-methyl-meth-acrylate (PMMA) by a single-shot femtosecond laser Bessel beam. The propagation of Bessel beam in PMMA (at 1.98 × 10⁸ m/s) and it induced cylindrical pressure wave expansion (at 3000-3950 m/s in radius) were observed during drilling processes. Also, it was unexpectedly found that the expansion of the cylindrical pressure wave in PMMA showed a linear relation with time and was insensitive to the laser energy fluctuation, quite different from the case in air. It was assumed that the energy insensitivity was due to the anisotropy of wave expansion in PMMA and the ambient air.

  4. Direct growth of CdSe semiconductor quantum dots in glass matrix by femtosecond laser beam (United States)

    Bell, G.; Filin, A. I.; Romanov, D. A.; Levis, R. J.


    Controllable, spatially inhomogeneous distributions of CdSe nanocrystals smaller than the exciton Bohr radius are grown in a glass matrix under combined action of sample heating (below the transformation temperature) and focused high-repetition femtosecond (fs) laser beam. Selective quantum dot precipitation is evidenced by position-dependent absorption and Raman spectra. The particle size is estimated as r = 2.1 ± 0.3 nm by comparing the measured absorption and Raman spectra with those obtained from the samples grown in glass by traditional heat-treatment procedure. Direct growth of CdSe quantum dots in glass is enabled by nonlinear excitation using a focused fs duration laser beam (as differentiated from other methods), and this opens an avenue for adjustable selective growth patterns.

  5. SEMICONDUCTOR INTEGRATED CIRCUITS Short locking time and low jitter phase-locked loop based on slope charge pump control (United States)

    Zhongjie, Guo; Youbao, Liu; Longsheng, Wu; Xihu, Wang; Wei, Tang


    A novel structure of a phase-locked loop (PLL) characterized by a short locking time and low jitter is presented, which is realized by generating a linear slope charge pump current dependent on monitoring the output of the phase frequency detector (PFD) to implement adaptive bandwidth control. This improved PLL is created by utilizing a fast start-up circuit and a slope current control on a conventional charge pump PLL. First, the fast start-up circuit is enabled to achieve fast pre-charging to the loop filter. Then, when the output pulse of the PFD is larger than a minimum value, the charge pump current is increased linearly by the slope current control to ensure a shorter locking time and a lower jitter. Additionally, temperature variation is attenuated with the temperature compensation in the charge pump current design. The proposed PLL has been fabricated in a kind of DSP chip based on a 0.35 μm CMOS process. Comparing the characteristics with the classical PLL, the proposed PLL shows that it can reduce the locking time by 60% with a low peak-to-peak jitter of 0.3% at a wide operation temperature range.

  6. Multiple-beams Mutually Pumped Phase Conjugation Generated by a Bridge Phase Conjugator in Photorefractive Ba1 - xSrxTi03 Crystal

    Institute of Scientific and Technical Information of China (English)

    QIU Yishen; LU Tuansun; HUANG Wenchai; ZHENG Zhiqiang; ZHUANG Jian; TANG Dingyuan


    A new method generating multiple-beams mutually pumped phase conjugation (MMPPC) in a photorefractive Bat- xSrxTiO3 crystal is demonstrated, in which a pumping beam is incident upon a-face of the crystal and two signal beams are introduced into + c face of the crystal with the almost same incident angle and position. The time evolution of the phase conjugations from signal beams and the dependence of phase-conjugate reflectivities on the input-beam intensity ratios are presented. Also, the amplitude coupled-wave equations based on the model of two interaction reigns is derived. The results obtained by numerical calculation of the corresponding coupled-wave equations show qualitative agreement with the experimental results.

  7. Pump-probe studies of radiation induced defects and formation of warm dense matter with pulsed ion beams (United States)

    Schenkel, T.; Persaud, A.; Gua, H.; Seidl, P. A.; Waldron, W. L.; Gilson, E. P.; Kaganovich, I. D.; Davidson, R. C.; Friedman, A.; Barnard, J. J.; Minior, A. M.


    We report results from the 2nd generation Neutralized Drift Compression Experiment at Berkeley Lab. NDCX-II is a pulsed, linear induction accelerator designed to drive thin foils to warm dense matter (WDM) states with peak temperatures of ~ 1 eV using intense, short pulses of 1.2 MeV lithium ions. Tunability of the ion beam enables pump-probe studies of radiation effects in solids as a function of excitation density, from isolated collision cascades to the onset of phase-transitions and WDM. Ion channeling is an in situ diagnostic of damage evolution during ion pulses with a sensitivity of channeled ions tracks lattice disorder evolution with a resolution of ~ 1 ns using fast current measurements. We will discuss pump-probe experiments with pulsed ion beams and the development of diagnostics for WDM and multi-scale (ms to fs) access to the materials physics of collision cascades e.g. in fusion reactor materials. Work performed under auspices of the US DOE under Contract No. DE-AC02-05CH11231.

  8. Examination of the Ion Beam Response of III-V Semiconductor Substrates (United States)

    Grossklaus, Kevin A.

    This work examines the response of the III-V materials to ion beam irradiation in a series of four experimental studies and describes the observed results in terms of the fundamental materials processes and properties that control ion-induced change in those compounds. Two studies investigate the use of Ga+ focused ion beam (FIB) irradiation of III-V substrate materials to create nanostructures. In the first, the creation of FIB induced group III nanodots on GaAs, InP, InAs, and AlAs is studied. The analysis of those results in terms of basic material properties and a simple nanodot growth model represents the first unified investigation of the fundamental processes that drive the nanodot forming behavior of the III-V compounds. The second nanostructure formation study reports the discovery and characterization of unique spike-like InAs nanostructures, termed "nanospikes," which may be useful for nanoscale electronic or thermoelectric applications. A novel method for controlling nanospike formation using InAs/InP heterostructures and film pre-patterning is developed, and the electrical properties of these ion erosion created nanostructures are characterized by in-situ TEM nanoprobe testing in a first-of-its-kind examination. The two remaining studies examine methods for using ion beam modification of III-V substrates to accommodate lattice-mismatched film growth with improved film properties. The first examines the effects of film growth on a wide range of different FIB created 3-D substrate patterns, and finds that 3-D surface features and patterns significantly alter film morphology and that growth on or near FIB irradiated regions does not improve film threading defect density. The second substrate modification study examines broad beam ion pre-implantation of GaAs wafers before InGaAs film growth, and is the first reported study of III-V substrate pre-implantation. Ar + pre-implantation was found to enhance the formation of threading defects in InGaAs films and

  9. Continuous-wave 1.55 $\\mu$m diode-pumped surface emitting semiconductor laser for broadband multiplex spectroscopy

    CERN Document Server

    Jacquemet, M; Guelachvili, G; Picqué, N; Sagnes, I; Strassner, M; Symonds, C; Garnache, Arnaud; Guelachvili, Guy; Jacquemet, Mathieu; Picqu\\'{e}, Nathalie; Sagnes, Isabelle; Strassner, Martin; Symonds, Cl\\'{e}mentine


    A room temperature operating Vertical External Cavity Surface Emitting Laser is applied around 1550 nm to intracavity laser absorption spectroscopy analyzed by time-resolved Fourier transform interferometry. At an equivalent pathlength of 15 km, the high resolution spectrum of the semiconductor disk laser emission covers 17 nm simultaneously. A noise equivalent absorption coefficient at one second averaging equal to 1.5 10^{-10} cm^{-1}.Hz^{-1/2} per spectral element is reported for the 65 km longest path length employed.

  10. SEMICONDUCTOR DEVICES A novel modified charge pumping method for trapped charge characterization in nanometer-scale devices (United States)

    Peng, Zhu; Liyang, Pan; Haiming, Gu; Fengying, Qiao; Ning, Deng; Jun, Xu


    A new modified method based on the charge pumping technique is proposed and adopted to extract the lateral profiles of oxide charges in an advanced MOSFET. A 0.12 μm SONOS device with 50 nm threshold voltage peak is designed and utilized to demonstrate the proposed method. The trapped charge distribution with a narrow peak can be precisely characterized with this method, which shows good consistency with the measured threshold voltage.

  11. Digital Square-Wave Frequency Modulated Microwave Sources for a Miniature Optically Pumped Cesium Beam Clock

    Institute of Scientific and Technical Information of China (English)

    CHEN Jingbiao; ZHU Chengjin; LIU Ge; WANG Fengzhi; WANG Yiqiu; YANG Donghai


    Three different digital frequencymodulated microwave sources have been designed andapplied to our miniature optically pumped cesiumbeam clock.The main features and their influenceon clock accuracy have been experimentally tested.Itis proved that a digital square-wave frequency modu-lated microwave source using a microprocessor con-trolled direct-digital frequency synthesizer (DDFS)for our miniature optically pumped cesium beamclock works well,the frequency short term stability2 × 10 11/x r and the long term stability 3.5 x 10-13 forone day sample time have been obtained.

  12. Molecular-beam epitaxy growth and structural characterization of semiconductor-ferromagnet heterostructures by grazing incidence X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Satapathy, D.K.


    The present work is devoted to the growth of the ferromagnetic metal MnAs on the semiconductor GaAs by molecular-beam epitaxy (MBE). The MnAs thin films are deposited on GaAs by molecular-beam epitaxy (MBE). Grazing incidence diffraction (GID) and reflection high-energy electron diffraction (RHEED) are used in situ to investigate the nucleation, evolution of strain, morphology and interfacial structure during the MBE growth. Four stages of the nucleation process during growth of MnAs on GaAs(001) are revealed by RHEED azimuthal scans. GID shows that further growth of MnAs films proceed via the formation of relaxed islands at a nominal thickness of 2.5 ML which increase in size and finally coalesce to form a continuous film. Early on, an ordered array of misfit dislocations forms at the interface releasing the misfit strain even before complete coalescence occurs. The fascinating complex nucleation process of MnAs on GaAs(0 0 1) contains elements of both Volmer-Weber and Stranski-Krastanov growth. A nonuniform strain amounting to 0.66%, along the [1 -1 0] direction and 0.54%, along the [1 1 0] direction is demonstrated from x-ray line profile analysis. A high correlation between the defects is found along the GaAs[1 1 0] direction. An extremely periodic array of misfit dislocations with a period of 4.95{+-}0.05 nm is formed at the interface along the [1 1 0] direction which releases the 7.5% of misfit. The inhomogeneous strain due to the periodic dislocations is confined at the interface within a layer of 1.6 nm thickness. The misfit along the [1 -1 0] direction is released by the formation of a coincidence site lattice. (orig.)

  13. Semiconductor laser

    Energy Technology Data Exchange (ETDEWEB)

    Ito, K.; Shyuue, M.


    A distributed feedback semiconductor laser is proposed which generates several beams with equal wavelengths in different directions. For this purpose, 1 millimeter grooves are cut into the surface of an n-type conductance GaAs plate in three different directions; these grooves form a diffraction grating. The center of this plate has no grooves and is bombarded by an He/Ne laser beam. The diffraction gratings provide resonance properties and generate laser beams with wavelengths of 8850, 9000 and 9200 angstroms.

  14. Synthesis of long group IV semiconductor nanowires by molecular beam epitaxy

    Directory of Open Access Journals (Sweden)

    Patriarche Gilles


    Full Text Available Abstract We report the growth of Si and Ge nanowires (NWs on a Si(111 surface by molecular beam epitaxy. While Si NWs grow perpendicular to the surface, two types of growth axes are found for the Ge NWs. Structural studies of both types of NWs performed with electron microscopies reveal a marked difference between the roughnesses of their respective sidewalls. As the investigation of their length dependence on their diameter indicates that the growth of the NWs predominantly proceeds through the diffusion of adatoms from the substrate up along the sidewalls, difference in the sidewall roughness qualitatively explains the length variation measured between both types of NWs. The formation of atomically flat {111} sidewalls on the <110>-oriented Ge NWs accounts for a larger diffusion length.

  15. Investigation of two-beam-pumped noncollinear optical parametric chirped-pulse amplification for the generation of few-cycle light pulses. (United States)

    Herrmann, Daniel; Tautz, Raphael; Tavella, Franz; Krausz, Ferenc; Veisz, Laszlo


    We demonstrate a new and compact Phi-plane-pumped noncollinear optical parametric chirped-pulse amplification (NOPCPA) scheme for broadband pulse amplification, which is based on two-beam-pumping (TBP) at 532 nm. We employ type-I phase-matching in a 5 mm long BBO crystal with moderate pump intensities to preserve the temporal pulse contrast. Amplification and compression of the signal pulse from 675 nm - 970 nm is demonstrated, which results in the generation of 7.1-fs light pulses containing 0.35 mJ energy. In this context, we investigate the pump-to-signal energy conversion efficiency for TBP-NOPCPA and outline details for few-cycle pulse characterization. Furthermore, it is verified, that the interference at the intersection of the two pump beams does not degrade the signal beam spatial profile. It is theoretically shown that the accumulated OPA phase partially compensates for wave-vector mismatch and leads to extended broadband amplification. The experimental outcome is supported by numerical split-step simulations of the parametric signal gain, including pump depletion and parametric fluorescence.

  16. Zeeman Electromagnetically Induced Transparency with crossed pump and probe beams: Small angle dependence (United States)

    Campbell, Kaleb; Madkhaly, Samaya; de Medeiros, Dillon; Bali, Samir; Macklin Quantum Information Sciences Collaboration


    Progress toward undergraduate oriented experiments on image storage in room-temperature atomic vapor using Electromagnetically Induced Transparency is described. Using a scanning longitudinal magnetic field technique we diagnose and suppress stray magnetic fields and polarization impurity. We consider the pump-probe angular dependence of the EIT signal but at much smaller angles of less than a milliradian.

  17. Efficient generation of cylindrically polarized beams in an Yb:YAG thin-disk laser enabled by a ring-shaped pumping distribution (United States)

    Dietrich, Tom; Rumpel, Martin; Graf, Thomas; Abdou Ahmed, Marwan


    The efficient generation of a cylindrically (radially or azimuthally) polarized LG01 mode was investigated using a ring-shaped pumping distribution in a high-power Yb:YAG thin-disk laser setup. This was realized by implementing a 300 mm long customized fused silica fiber capillary in the pump beam path of the pumping optics of a thin-disk laser. Furthermore, a grating waveguide mirror based on the leaky-mode coupling mechanism was used as one of the cavity end mirrors to allow sufficient reduction of the reflectivity of the polarization state to be suppressed in the resonator. In order to achieve efficient laser operation, an optimized mode overlap between the ring-shaped pump spot and the excited first order Laguerre-Gaussian doughnut mode is required. This was investigated theoretically by analyzing the intensity distribution generated by different fiber geometries using a commercially raytracing software (Zemax). The output power, polarization state and efficiency of the emitted laser beam were compared to that obtained with a standard flattop pumping distribution. In particular, the thermal behavior of the disk was investigated since the excessive fluorescence caused by the non-saturated excitation in the center of the homogeneously pumped disk leads to a strong heating of the crystal. This considerable heating source is avoided in the case of the ring-shaped pumping and a reduction of the temperature increase on the disk surface of about 21% (at 280 W of pump power) was observed. This should allow higher pump power densities without increasing the risk of damaging the disk or distorting the polarization purity. With a laser efficiency of 41.2% to be as high as in the case of the flattop pumping, a maximum output power of 107 W was measured.

  18. High-sensitivity operation of single-beam optically pumped magnetometer in a kHz frequency range (United States)

    Savukov, I.; Kim, Y. J.; Shah, V.; Boshier, M. G.


    Optically pumped magnetometers (OPM) can be used in various applications, from magnetoencephalography to magnetic resonance imaging and nuclear quadrupole resonance (NQR). OPMs provide high sensitivity and have the significant advantage of non-cryogenic operation. To date, many magnetometers have been demonstrated with sensitivity close to 1 fT, but most devices are not commercialized. Most recently, QuSpin developed a model of OPM that is low cost, high sensitivity, and convenient for users, which operates in a single-beam configuration. Here we developed a theory of single-beam (or parallel two-beam) magnetometers and showed that it is possible to achieve good sensitivity beyond their usual frequency range by tuning the magnetic field. Experimentally we have tested and optimized a QuSpin OPM for operation in the frequency range from DC to 1.7 kHz, and found that the performance was only slightly inferior despite the expected decrease due to deviation from the spin-exchange relaxation-free regime.

  19. Applications of Semiconductor Lasers

    Institute of Scientific and Technical Information of China (English)

    LI Te; SUN Yan-fang; NING Yong-qiang; WANG Li-jun


    An overview of the applications of semiconductor lasers is presented. Diode lasers are widely used today,and the most prevalent use of the laser is probably in CD and DVD drives for computers and audio/video media systems. Semiconductor lasers are also used in many other fields ranging from optical fiber communications to display,medicine and pumping sources.

  20. Diode-pumped optical parametric oscillator. (United States)

    Geiger, A R; Hemmati, H; Farr, W H; Prasad, N S


    Diode-pumped optical parametric oscillation has been demonstrated for the first time to our knowledge in a single Nd:MgO:LiNbO(3) nonlinear crystal. The crystal is pumped by a semiconductor diode laser array at 812 nm. The Nd(3+) ions absorb the 812-nm radiation to generate 1084-nm laser oscillation. On internal Q switching the 1084-nm radiation pumps the LiNbO(3) host crystal that is angle cut at 46.5 degrees and generates optical parametric oscillation. The oscillation threshold that is due to the 1084-nm laser pump with a pulse length of 80 ns in a 1-mm-diameter beam was measured to be approximately 1 mJ and produced 0.5-mJ output at 3400-nm signal wavelength.

  1. Characterization of optically excited semiconductors by phase-resolved pump-probe spectroscopy; Charakterisierung optisch angeregter Halbleiter mit phasenaufgeloester Pump-Probe-Spektroskopie

    Energy Technology Data Exchange (ETDEWEB)

    Seemann, M.


    This thesis aims to present new experimentally and theoretically verified statements about the many-body effects in thin Zinc Selenide layers and to discuss the various techniques applied in the experiments. Centred in this thesis is the investigation of ultrafast nonlinear effects in the response of thin Zinc Selenide layers on their optical excitation with ultrashort laser pulses. The experiments address the regime of quantum coherence and thermalisation of the excitation. In the energy range of the band gap the response is determined by the propagation of exciton polaritons in the samples. The dynamics of the interactions between the polaritons and the particles of the solid are investigated by conducting pump-probe experiments. This thesis extends and surpasses previous work in that the reflected light is completely analysed in its classical phase and amplitude. Thus all the information in the electromagnetic field in the temporal and spectral domain is available. It is found that especially not just the power spectrum of the reflected light is much structured but the spectral phase too. The spectral phase reflects directly the carrier-density dependent of the polariton dispersion while the temporal field, characterised by the beating of slowly propagating polaritons, does not show dramatic carrier-density depended changes. Phase resolved measurement of the reflected field is performed with the technique of Spectral Interferometry which is adapted to the experiment and tested on correctness. The measured electromagnetic fields are interpreted with classical and a semi-classical microscopic models. Further is shown how these results relate to recent microscopic quantum mechanical models. (orig.)

  2. Investigation of narrow-band semiconductor quantum well structures using a synchronously-pumped optical parametric oscillator

    CERN Document Server

    Marsden, P A


    Measurements of spin relaxation processes were made in the technologically interesting InGaAs/lnP quantum wells system. The first non-linear pump and probe measurements were performed in a single 80A lattice-matched InGaAs/lnP quantum well layer. To make these measurements a synchronously-pumped parametric oscillator was constructed, using periodically-poled lithium niobate as its non-linear element. Spin relaxation measurements on InGaAs/lnP quantum wells at low (4K) temperature reveal spin-lifetimes of order 50ps, similar to those measured in the wider-gap GaAs/AIGaAs system. At room temperature the spin-lifetimes were measured to be 5ps, an order of magnitude faster than those for GaAs/AIGaAs or InGaAs/lnAIAs quantum wells of similar specification. Investigations of dominant carrier species and their associated spin relaxation were made as a function of temperature. A model was constructed for comparison to the experimental data showing the dominance of excitons at low temperature, with un-bound electron-h...

  3. Development of a Pump-Probe System using a Non-Coated ZnSe Beam Splitter Cube for an MIR-FEL

    CERN Document Server

    Heya, Manabu; Horiike, Hiroshi; Ishii, Katsonuri; Suzuki, Sachiko


    A pump-probe technique is essential for a proper understanding of laser interaction with tissue and material. Our pump-probe system divides the incident mid-infrared Free Electron Laser (MIR-FEL) into two beams with equal intensity, and crosses simultaneously the two incoming beams at the same position. One is for a pump beam, another is for a probe beam. Time-resolved absorption spectroscopy involving this technique gives us information on the vibrational dynamics of molecules. We have developed this system for an MIR-FEL using a non-coating ZnSe beam splitter cube. The beam splitter cube is composed of two ZnSe prisms in the shape like a trapezoid. The two pulses with equal intensity are generated due to Fresnel reflection and transmission at the boundary between two prisms, then are reflected due to total reflection at other side boundaries between each prism and air, and illuminate simultaneously the same spot. We have conducted a proof-of-concept of experiment of this system using an MIR-FEL. We showed t...

  4. Efficient pump beam shaping for high-power thin-disk laser systems. (United States)

    Pereira, Rui; Weichelt, Birgit; Liang, Dawei; Morais, Paulo J; Gouveia, Helena; Abdou-Ahmed, Marwan; Voss, Andreas; Graf, Thomas


    We report a beam-shaping technique whereby the output power from a high-power laser-diode stack is efficiently coupled, reconfigured, and transmitted to a thin-disk laser by means of a compact optical fiber bundle. By using this technique, the power density is increased by a factor of 2 when compared to direct coupling with a octagonal fused silica rod while the numerical aperture is kept constant. Transmission efficiency of 80% was measured for the beam shaper without antireflection coating. The top-hat distribution is numerically calculated at the thin-disk laser crystal.

  5. Implementation of intra-cavity beam shaping technique to enhance pump efficiency

    CSIR Research Space (South Africa)

    Litvin, IA


    Full Text Available of the resonator concept. M1 and M2 are flat mirrors; FPTE and FFTB are the lossless phase transformation elements at mirror M1 and M2 respectively. To solve a given problem we must solve the problem of transforming a Super?Gaussian (SG) beam into FT beam... in the cavity. We consider a system consisting of a lens with focal length f and a lossless phase transformation element ?(r) on the plane of mirror M1 which are positioned as a doublet (see fig. 1) [5]. The field at the focal plane of the lens (mirror M2 (see...

  6. Ultrafast supercontinuum fiber-laser based pump-probe scanning MOKE microscope for the investigation of electron spin dynamics in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution

    CERN Document Server

    Henn, T; Ossau, W; Molenkamp, L W; Biermann, K; Santos, P V


    We describe a two-color pump-probe scanning magneto-optical Kerr effect (MOKE) microscope which we have developed to investigate electron spin phenomena in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution. The key innovation of our microscope is the usage of an ultrafast `white light' supercontinuum fiber-laser source which provides access to the whole visible and near-infrared spectral range. Our Kerr microscope allows for the independent selection of the excitation and detection energy while avoiding the necessity to synchronize the pulse trains of two separate picosecond laser systems. The ability to independently tune the pump and probe wavelength enables the investigation of the influence of excitation energy on the optically induced electron spin dynamics in semiconductors. We demonstrate picosecond real-space imaging of the diffusive expansion of optically excited electron spin packets in a (110) GaAs quantum well sample to illustrate the capabilities of t...

  7. Many-sided electron beam pumping of high-power lasers (United States)

    Ryzhov, V. V.; Turchanovskii, I. Y.


    To study the performance of high power lasers with a many- sided electron beam injection, MUFLON-code has been developed. This code was used to choose and design optimum injection schemes for the excitation of the high-power gas lasers developed at the High Current Electronics Institute.

  8. Nonlinear gain amplification due to two-wave mixing in a broad-area semiconductor amplifier with moving gratings

    DEFF Research Database (Denmark)

    Chi, Mingjun; Huignard, J.-P.; Petersen, Paul Michael


    . The results show that the optical gain of the amplifier is affected by both the moving phase grating and the moving gain grating, and there is energy exchange between the pump and signal beams. Depending on the moving direction of the gratings and the anti-guiding parameter, the optical gain may increase......The two-wave mixing in a broad-area semiconductor amplifier with moving gratings is investigated theoretically, where a pump beam and a signal beam with different frequencies are considered, thus both a moving phase grating and a moving gain grating are induced in the amplifier. The coupled...

  9. Amplification of picosecond pulse by electron-beam pumped KrF laser amplifiers. Denshi beam reiki KrF laser zofukuki ni yoru piko byo pulse no zofuku

    Energy Technology Data Exchange (ETDEWEB)

    Okuda, I.; Tomie, T.; Owadano, Y.; Yano, M. (Electrotechnical Laboratory, Tsukuba (Japan))


    Experiments on the amplification of a picosecond pulse by electron-beam pumped KrF laser amplifiers were carried out for the purpose of its application to the field such as excitation light source for soft X-ray laser which requires large energy besides peak power. The picosecond pulse was amplified by a discharge pumped KrF amplifier and two electron-beam pumped KrF amplifiers(at the middle stage and the final stage). The energy of 4J, which was the largest energy for short pulse excimer laser so far, was obtained by these devices. About 90% of the window area of the final amplifier with 29cm diameter was filled by the input beam, and energy density of the picosecond beam reached 3.9 times saturation energy density. Measured energy of amplified spontaneous emission(ASE) showed good agreement with the theoretically estimated value. Most of ASE was derived from the discharge pumped laser as the first amplifier. As for the focused power density, the power density ratio of the picosecond pulse to ASE was estimated to be as large as 10{sup 5}. 11 refs., 4 figs.

  10. Improvement of the Spatial Amplitude Isotropy of a ^4He Magnetometer Using a Modulated Pumping Beam (United States)

    Chéron, B.; Gilles, H.; Hamel, J.; Moreau, O.; Noël, E.


    Optically pumped magnetometers are scalar magnetometers. Contrary to vectoriel magnetometers, they measure the total magnetic field whatever the direction of the sensor. However, for some orientations of the magnetometer with respect to the magnetic field direction, the resonant signal vanishes and the measurement is impossible. In this paper we present a simple solution to reduce the amplitude spatial anisotropy and apply it to a ^4He magnetometer developed in our Laboratory. Les magnétomètres à pompage optique sont des magnétomètres scalaires. Contrairement aux magnétomètres vectoriels, ils mesurent le module du champ magnétique quelle que soit l'orientation du capteur dans l'espace. Cependant, pour certaines orientations du magnétomètre par rapport à la direction du champ à mesurer, l'amplitude du signal de résonance s'annule et la mesure devient impossible. Dans cet article, nous présentons une solution simple pour réduire l'anisotropie spatiale d'amplitude et nous l'appliquons à un magnétomètre à hélium-4 développé dans notre Laboratoire.

  11. Optically-electrically pumped THz source (United States)

    Haji-Saeed, Bahareh; Khoury, Jed; Buchwald, Walter; Woods, Charles; Wentzell, Sandra; Krejca, Brian; Kierstead, John


    In this paper, we propose a design for a widely tunable solid-state optically and electrically pumped THz source based on the Smith-Purcell free-electron laser. Our design consists of a thin dielectric layer sandwiched between an upper corrugated structure and a lower layer of thin metal, semiconductor, or high electron mobility material. The lower layer is for current streaming, which replaces the electron beam in the Smith-Purcell free-electron laser design. The upper layer consists of two micro-gratings for optical pumping, and a nano-grating to couple with electrical pumping in the lower layer. The optically generated surface plasmon waves from the upper layer and the electrically induced surface plasmon waves from the lower layer are then coupled. Emission enhancement occurs when the plasmonic waves in both layers are resonantly coupled.

  12. Detection of slow atoms confined in a Cesium vapor cell by spatially separated pump and probe laser beams

    CERN Document Server

    Todorov, Petko; Maurin, Isabelle; Saltiel, Solomon; Bloch, Daniel


    The velocity distribution of atoms in a thermal gas is usually described through a Maxwell-Boltzman distribution of energy, and assumes isotropy. As a consequence, the probability for an atom to leave the surface under an azimuth angle {\\theta} should evolve as cos {\\theta}, in spite of the fact that there is no microscopic basis to justify such a law. The contribution of atoms moving at a grazing incidence towards or from the surface, i.e. atoms with a small normal velocity, here called "slow" atoms, reveals essential in the development of spectroscopic methods probing a dilute atomic vapor in the vicinity of a surface, enabling a sub-Doppler resolution under a normal incidence irradiation. The probability for such "slow" atoms may be reduced by surface roughness and atom-surface interaction. Here, we describe a method to observe and to count these slow atoms relying on a mechanical discrimination, through spatially separated pump and probe beams. We also report on our experimental progresses toward such a g...

  13. Pulsed electron-beam-pumped laser based on AlGaN/InGaN/GaN quantum-well heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Gamov, N A; Zhdanova, E V; Zverev, M M; Peregudov, D V; Studenov, V B [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation); Mazalov, A V; Kureshov, V A; Sabitov, D R; Padalitsa, A A; Marmalyuk, A A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation)


    The parameters of pulsed blue-violet (λ ≈ 430 nm at T = 300 K) lasers based on an AlGaN/InGaN/GaN structure with five InGaN quantum wells and transverse electron-beam pumping are studied. At room temperature of the active element, the minimum electron energy was 9 keV and the minimum threshold electron beam current density was 8 A cm{sup -2} at an electron energy of 18 keV. (lasers)

  14. Particularities of optical pumping effects in cold and ultra-slow beams of Na and Cs in the case of cyclic transitions

    KAUST Repository

    Bruvelis, M.


    The time-dependent population dynamics of hyperfine (HF) levels of n2p3/2 states is examined for cyclic transitions in alkali atoms. We study a slow and cold atomic beam of Na (n = 3) and Cs (n = 6), taking into account the long interaction time of light with atoms (~200 μs) inside the resonant laser beam. Simple analytical expressions for the populations of the excited states and for the intensities of the absorption lines are derived for a three-level system model. We show that at moderate pump laser power the mixing of HF levels is sufficient to form a flow of population from a cyclic transition to partially open transitions. We discuss various phenomena associated with the evolution of optical pumping that cannot be explained by general analysis of two-level system model.

  15. Diode-pumped dual-wavelength Nd:LSO laser at 1059 and 1067  nm with nearly diffraction-limited beam quality. (United States)

    Huang, Xiaoxu; Lan, Jinglong; Lin, Zhi; Wang, Yi; Xu, Bin; Xu, Huiying; Cai, Zhiping; Xu, Xiaodong; Zhang, Jian; Xu, Jun


    We report a diode-pumped continuous-wave simultaneous dual-wavelength Nd:LSO laser at 1059 and 1067 nm. By employing a specially coated output coupler with relatively high transmissions at high-gain emission lines of 1075 and 1079 nm, the two low-gain emission lines, 1059 and 1067 nm, can be achieved, for the first time to our knowledge, with maximum output power of 1.27 W and slope efficiency of about 29.2%. The output power is only limited by the available pump power. Output beam quality is also measured to be about 1.19 and 1.21 of the beam propagation factors in the x and y directions, respectively.

  16. Optical Orientation in Ferromagnet/Semiconductor Hybrids


    Korenev, V. L.


    The physics of optical pumping of semiconductor electrons in the ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of the ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of the semiconductor. Spin-spin interactions near the interface ferromagnet/semiconductor play crucial role in the optical readout and the manipulation of ferromagnetism.

  17. Wavelength-resonant surface-emitting semiconductor laser (United States)

    Brueck, Steven R. J.; Schaus, Christian F.; Osinski, Marek A.; McInerney, John G.; Raja, M. Yasin A.; Brennan, Thomas M.; Hammons, Burrell E.


    A wavelength resonant semiconductor gain medium is disclosed. The essential feature of this medium is a multiplicity of quantum-well gain regions separated by semiconductor spacer regions of higher bandgap. Each period of this medium consisting of one quantum-well region and the adjacent spacer region is chosen such that the total width is equal to an integral multiple of 1/2 the wavelength in the medium of the radiation with which the medium is interacting. Optical, electron-beam and electrical injection pumping of the medium is disclosed. This medium may be used as a laser medium for single devices or arrays either with or without reflectors, which may be either semiconductor or external.

  18. Merged beam laser design for reduction of gain-saturation and two-photon absorption in high power single mode semiconductor lasers. (United States)

    Lysevych, M; Tan, H H; Karouta, F; Fu, L; Jagadish, C


    In this paper we report a method to overcome the limitations of gain-saturation and two-photon absorption faced by developers of high power single mode InP-based lasers and semiconductor optical amplifiers (SOA) including those based on wide-waveguide or slab-coupled optical waveguide laser (SCOWL) technology. The method is based on Y-coupling design of the laser cavity. The reduction in gain-saturation and two-photon absorption in the merged beam laser structures (MBL) are obtained by reducing the intensity of electromagnetic field in the laser cavity. Standard ridge-waveguide lasers and MBLs were fabricated, tested and compared. Despite a slightly higher threshold current, the reduced gain-saturation in MBLs results in higher output power. The MBLs also produced a single spatial mode, as well as a strongly dominating single spectral mode which is the inherent feature of MBL-type cavity.

  19. Two-dimensional semiconductor HfSe{sub 2} and MoSe{sub 2}/HfSe{sub 2} van der Waals heterostructures by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Aretouli, K. E.; Tsipas, P.; Tsoutsou, D.; Marquez-Velasco, J.; Xenogiannopoulou, E.; Giamini, S. A.; Vassalou, E.; Kelaidis, N.; Dimoulas, A., E-mail: [Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos,” 15310, Aghia Paraskevi, Athens (Greece)


    Using molecular beam epitaxy, atomically thin 2D semiconductor HfSe{sub 2} and MoSe{sub 2}/HfSe{sub 2} van der Waals heterostructures are grown on AlN(0001)/Si(111) substrates. Details of the electronic band structure of HfSe{sub 2} are imaged by in-situ angle resolved photoelectron spectroscopy indicating a high quality epitaxial layer. High-resolution surface tunneling microscopy supported by first principles calculations provides evidence of an ordered Se adlayer, which may be responsible for a reduction of the measured workfunction of HfSe{sub 2} compared to theoretical predictions. The latter reduction minimizes the workfunction difference between the HfSe{sub 2} and MoSe{sub 2} layers resulting in a small valence band offset of only 0.13 eV at the MoSe{sub 2}/HfSe{sub 2} heterointerface and a weak type II band alignment.

  20. Fiber-based multiple-beam reflection interferometer for single-longitudinal-mode generation in fiber laser based on semiconductor optical amplifier (United States)

    Terentyev, V. S.; Simonov, V. A.; Babin, S. A.


    A technique of single-longitudinal-mode selection in a fiber laser by means of a fiber multiple-beam reflection interferometer (FRI) has been experimentally demonstrated for the first time. The laser is based on a semiconductor optical amplifier placed in a linear fiber cavity formed by a fiber Bragg grating (FBG), and the FRI generates at 1529.24 nm with output power of 1 mW in single-frequency regime with a linewidth of about 217 kHz and polarization extinction ratio of  >30 dB. The FRI technique potentially enables fast tuning (within the FBG bandwidth of ~0.9 nm in our case) by varying the base length of the FRI that can be used in a number of practical applications.

  1. Electrically controlled Goos-Hänchen shift of a light beam reflected from the metal-insulator-semiconductor structure. (United States)

    Luo, Changyou; Guo, Jun; Wang, Qingkai; Xiang, Yuanjiang; Wen, Shuangchun


    We proposed a scheme to manipulate the Goos-Hänchen shift of a light beam reflected from the depletion-type device via external voltage bias. It is shown that the lateral shift of the reflected probe beam can be easily controlled by adjusting the reverse voltage bias and the incidence angle. Using this scheme, the lateral shift can be tuned from negative to positive, without changing the original structure of the depletion-type device. Numerical calculations further indicate that the influence of structure parameters and light wavelength can be reduced via readjustment of the reverse bias. The proposed structure has the potential application for the integrated electronic devices.

  2. Formation of the active medium in high-power repetitively pulsed gas lasers pumped by an electron-beam-controlled discharge (United States)

    Bulaev, V. D.; Lysenko, S. L.


    A high-power repetitively pulsed e-beam-controlled discharge CO2 laser is simulated numerically; the simulation results are compared with experimental data. Optimal sizes and design of electrodes and configuration of the external magnetic field are found, which allow one to introduce no less than 90% electric pump energy into a specified volume of the active medium, including the active volume of a laser with an aperture of 110 × 110 cm. The results obtained can also be used to design other types of highpower gas lasers.

  3. Generation of 220 mJ nanosecond pulses at a 10 Hz repetition rate with excellent beam quality in a diode-pumped Yb:YAG MOPA system. (United States)

    Wandt, Christoph; Klingebiel, Sandro; Siebold, Mathias; Major, Zsuzsanna; Hein, Joachim; Krausz, Ferenc; Karsch, Stefan


    A novel all-diode-pumped master oscillator power amplifier system based on Yb:YAG crystal rods has been developed. It consists of a Q-switched oscillator delivering 3 mJ, 6.4 ns pulses at a 10 Hz repetition rate and an additional four-pass amplifier, which boosts the output energy to 220 mJ, while a close to TEM(00) beam quality could be observed. Additionally a simulation of the amplification was written that allows for further scaling considerations.

  4. Researching the 915 nm high-power and high-brightness semiconductor laser single chip coupling module (United States)

    Wang, Xin; Wang, Cuiluan; Wu, Xia; Zhu, Lingni; Jing, Hongqi; Ma, Xiaoyu; Liu, Suping


    Based on the high-speed development of the fiber laser in recent years, the development of researching 915 nm semiconductor laser as main pumping sources of the fiber laser is at a high speed. Because the beam quality of the laser diode is very poor, the 915 nm laser diode is generally based on optical fiber coupling module to output the laser. Using the beam-shaping and fiber-coupling technology to improve the quality of output beam light, we present a kind of high-power and high-brightness semiconductor laser module, which can output 13.22 W through the optical fiber. Based on 915 nm GaAs semiconductor laser diode which has output power of 13.91 W, we describe a thoroughly detailed procedure for reshaping the beam output from the semiconductor laser diode and coupling the beam into the optical fiber of which the core diameter is 105 μm and the numerical aperture is 0.18. We get 13.22 W from the output fiber of the module at 14.5 A, the coupling efficiency of the whole module is 95.03% and the brightness is 1.5 MW/cm2 -str. The output power of the single chip semiconductor laser module achieves the advanced level in the domestic use.

  5. Extending the detection limit of dopants for focused ion beam prepared semiconductor specimens examined by off-axis electron holography

    DEFF Research Database (Denmark)

    Cooper, David; Rivallin, Pierrette; Hartmann, Jean-Michel;


    Silicon specimens containing p-n junctions have been prepared for examination by off-axis electron holography using focused ion beam (FIB) milling. FIB milling modifies the surfaces of the specimens due to gallium implantation and the creation of defects which has the effect of reducing the activ...

  6. Stable High Power and High Beam Quality Diode-Side-Pumped Continuous-Wave Intracavity Frequency-Doubled Nd:YAG Laser

    Institute of Scientific and Technical Information of China (English)

    CHENG Xian-Kun; ZHOU Yong; CUI Qian-Jin; YANG Feng; BO Yong; PENG Qin-Jun; CUI Da-Fu; XU Zu-Yan


    We report a stable high power and high beam quality diode-side-pumped cw green laser from intracavity frequency-doubled Nd:YAG laser with KTP.By using a L-shaped concave-convex resonator,designed with two Nd:YAG rods birefringence compensation,a large fundamental mode size in the laser crystal arid a tight focus in the nonlinear crystal could be obtained simultaneously.The green laser delivers a maximum 532nm output power of 23.2 W.Under 532 nm output power of 20.9 W,the beam quality factor is measured to be 4.1,and the fluctuation of the output power is less than 1.4% in an hour.

  7. Strain at a semiconductor nanowire-substrate interface studied using geometric phase analysis, convergent beam electron diffraction and nanobeam diffraction

    DEFF Research Database (Denmark)

    Persson, Johan Mikael; Wagner, Jakob Birkedal; Dunin-Borkowski, Rafal E.


    Semiconductor nanowires have been studied using electron microscopy since the early days of nanowire growth, e.g. [1]. A common approach for analysing nanowires using transmission electron microscopy (TEM) involves removing them from their substrate and subsequently transferring them onto carbon...... films. This sample preparation method is fast and usually results in little structural change in the nanowires [2]. However, it does not provide information about the interface between the nanowires and the substrate, who’s physical and electrical properties are important for many modern applications...... of nanowires. In particular, strain and crystallographic defects can have a major influence on the electronic structure of the material. In improved method for the characterization of such interfaces would be valuable for optimizing and understanding the transport properties of devices based on nanowires. Here...

  8. Beam quality management by periodic reproduction of wavefront aberrations in end-pumped Nd:YVO4 laser amplifiers. (United States)

    Liu, Bin; Liu, Chong; Shen, Lifeng; Wang, Chunhua; Ye, Zhibin; Liu, Dong; Xiang, Zhen


    A method for beam quality management is presented in a master oscillator power amplifier (MOPA) using Nd:YVO4 as the gain medium by extra-cavity periodic reproduction of wavefront aberrations. The wavefront aberration evolution of the intra-cavity beams is investigated for both symmetrical and asymmetrical resonators. The wavefront aberration reproduction process is successfully realized outside the cavity in four-stage amplifiers. In the MOPA with a symmetrical oscillator, the laser power increases linearly and the beam quality hardly changes. In the MOPA with an asymmetrical oscillator, the beam quality is deteriorated after the odd-stage amplifier and is improved after the even-stage amplifier. The wavefront aberration reproduction during the extra-cavity beam propagation in the amplifiers is equivalent to that during the intra-cavity propagation. This solution helps to achieve the effective beam quality management in laser amplifier chains.

  9. Full characterization of a high-power semiconductor disk laser beam with simultaneous capture of optimally sized focus and farfield. (United States)

    Borgentun, Carl; Bengtsson, Jörgen; Larsson, Anders


    We report on a beam characterization method that is based on the simultaneous measurement of the focus field and the farfield, thus avoiding problems with beam fluctuations during the measurement. By using reflections from both sides of a planoconvex lens, the method implements two branches of an optical system working simultaneously. Also, by letting the planoconvex lens be antireflection treated, and by allowing for both of the reflected fields to fill large and approximately equal areas on a camera detector array, the method significantly lowers the intensity onto the detector array, thus minimizing the need for additional disturbing attenuation filters to avoid camera saturation. In the numerical retrieval of the phase distribution, based on the measured intensity distributions of the focus and farfield, iterative propagation between the two branches is performed. The phase retrieval uses the two-step algorithm for the numerical field propagation conveniently providing an arbitrary choice of sampling distance in each plane.

  10. Photon antibunching and nonlinear effects for a quantum dot coupled to a semiconductor cavity (United States)

    Bello, F.; Whittaker, D. M.


    The models presented simulate pumping techniques that can be used on modern semiconductor devices which are capable of coupling a quantum dot and cavity mode in order to determine a more efficient method of producing a single-photon emitter while taking into consideration typical parameters which are achievable given today’s standards of coupling strength. Cavity quantum electrodynamics are incorporated in the calculations as we compare various pumping schemes for the system that either use on-resonant laser excitation or nonresonant excitation due to a wetting layer. In particular, we look to study how antibunching effects change for each method as the cavity finesse is increased toward the strong coupling regime. Experimentally these studies are equivalent to nonlinear pump-probe measurements, where a strong pump, either resonant or nonresonant, is used to excite the coupled system, and the resulting state is characterized using a weak, resonant probe beam.

  11. A Bidirectional, Diode-Pumped, Passively Mode-Locked Nd:YVO4 Ring Laser with a Low-Temperature-Grown Semiconductor Saturable Absorber Mirror

    Institute of Scientific and Technical Information of China (English)

    CAI Zhi-Qiang; YAO Jian-Quan; WANG Peng; WANG Yong-Gang; ZHANG Zhi-Gang


    We report the operation of a bidirectional picosecond pulsed ring Nd:YVO4 laser based on a low-temperaturegrown semiconductor saturable absorber mirror. Except for the laser crystal, the six-mirror ring laser cavity has no intra-cavity elements such as focusing lens or mirror. The bidirectional mode locked pluses are obtained at the repetition rate of 117.5MHz, pulse duration of Sips, power of 2×200 mW.

  12. Low temperature growth of Co{sub 2}MnSi films on diamond semiconductors by ion-beam assisted sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Nishiwaki, M.; Ueda, K., E-mail:; Asano, H. [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)


    High quality Schottky junctions using Co{sub 2}MnSi/diamond heterostructures were fabricated. Low temperature growth at ∼300–400 °C by using ion-beam assisted sputtering (IBAS) was necessary to obtain abrupt Co{sub 2}MnSi/diamond interfaces. Only the Co{sub 2}MnSi films formed at ∼300–400 °C showed both saturation magnetization comparable to the bulk values and large negative anisotropic magnetoresistance, which suggests half-metallic nature of the Co{sub 2}MnSi films, of ∼0.3% at 10 K. Schottky junctions formed using the Co{sub 2}MnSi films showed clear rectification properties with rectification ratio of more than 10{sup 7} with Schottky barrier heights of ∼0.8 eV and ideality factors (n) of ∼1.2. These results indicate that Co{sub 2}MnSi films formed at ∼300–400 °C by IBAS are a promising spin source for spin injection into diamond semiconductors.

  13. A ΔE-E semiconductor detector combined with CsI(Tl) crystal for monitoring the relative electrons flux generated in interaction of accelerated nuclei beam on thin targets (United States)

    Cruceru, M.; Afanasiev, S.; Dryablov, D.; Dubinchik, B.; Igamkulov, Z.


    Experimental data are presented, obtained with a ΔE-E semiconductor detector combined with a CsI(Tl) inorganic scintillator crystal. The interaction between a beam of accelerated nuclei and thin targets is analyzed. We show that, as a result of this interaction, the secondary particles, including δ-electrons, are generated. In the case of δ-electrons it is possible to study the beam characteristics and the nature of interaction processes, which is of great interest in high-energy interaction.

  14. Molecular beam epitaxy engineered III-V semiconductor structures for low-power optically addressed spatial light modulators (United States)

    Larsson, Anders G.; Maserjian, Joseph


    Device approaches are investigated for optically addressed SLMs based on molecular-beam epitaxy (MBE) engineered III-V materials and structures. Strong photooptic effects can be achieved in periodically delta-doped multiple-quantum-well structures, but are still insufficient for high-contrast modulation with only single- or double-pass absorption through active layers of practical thickness. The asymmetric Fabry-Perot cavity approach is employed to permit extinction of light due to interference of light reflected from the front and back surfaces of the cavity. This approach is realized with an all-MBE-grown structure consisting of GaAs/AlAs quarter-wave stack reflector grown over the GaAs substrate as the high reflectance mirror and the GaAs surface as the low reflectance mirror. High-contrast modulation is achieved using a low-power InGaAs/GaAs quantum well laser for the control signal.

  15. Grating THz laser with optical pumping (United States)

    Khoury, Jed; Haji-saeed, Bahareh; Woods, Charles; Kierstead, John


    In this paper, we present a design for a widely tunable solid-state optically and electrically pumped THz laser based on the Smith-Purcell free-electron laser. In the free-electron laser, an energetic electron beam pumps a metallic grating to generate surface plasmons. Our solid-state optically pumped design consists of a thin layer of dielectic, such as SiNx, sandwiched between a corrugated structure and a thin metal or semiconductor layer. The lower layer is for current streaming, and replaces the electron beam in the original design. The upper layer consists of one micro-grating for coupling the electromagnetic field in, another for coupling out, and a nano-grating for coupling with the current in the lower layer for electromagnetic field generation. The surface plasmon waves generated from the upper layer by an external electromagnetic field, and the lower layer by the applied current, are coupled. Emission enhancement occurs when the plasmonic waves in both layers are resonantly coupled.

  16. Room-temperature electrically pumped near-infrared random lasing from high-quality m-plane ZnO-based metal-insulator-semiconductor devices



    Epitaxial m-plane ZnO thin films have been deposited on m-plane sapphire substrates at a low temperature of 200°C by atomic layer deposition. A 90° in-plane rotation is observed between the m-plane ZnO thin films and the sapphire substrates. Moreover, the residual strain along the ZnO [−12-10] direction is released. To fabricate metal-insulator-semiconductor devices, a 50-nm Al2O3 thin film is deposited on the m-plane ZnO thin films. It is interesting to observe the near-infrared random lasin...

  17. Effect of Stoichiometry and Absorption on Self-Pumped Two-Beam Coupling Gain and Photovoltaic Fields in LiNbO3:Fe (United States)

    Banerjee, Hans; Cook, Gary; Banerjee, Partha; Basun, Sergey; Carns, Jennifer; Wechsler, Barry; Scripsick, Michael; Evans, Dean


    The variation of self-pumped two-beam coupling gain in LiNbO3:Fe crystals is investigated, using a CW Verdi 532 nm laser, as a function of absorption coefficients, α, and stoichiometry. The 81 crystals tested contain either 0.02% or 0.05% Fe concentrations and are either stoichiometric, intermediate, congruent, or Li deficient. These compositions include a range of α varying between 0.1 and 16 cm-1. Experimental coupling efficiency results exhibit a dependence on both composition and α; these parameters influence the photovoltaic field, which plays a large role in coupling efficiencies. Experimental results are compared with a mathematical model using a focused geometry, and values for the photovoltaic fields as a function of composition are extracted.

  18. Tunable Infrared Semiconductor Lasers (United States)


    Lett. 81, 406-408 (2002). [20] M. Ito and T. Kimura, “Oscillation properties of AlGaAs DH Lasrs with an external grating,” IEEE J. Quant. Elec- tron...tuning range has been demonstrated on a large area index-coupled, optically pumped mid-infrared type-II semiconductor distributed feedback (DFB) laser...lithography (IL) technique is used to pattern this chirped grating with two coherent spherical waves. A new grating fabrication optical arrangement

  19. A mirror-less, multi-beam photonic free-electron laser oscillator pumped far beyond threshold

    NARCIS (Netherlands)

    van der Slot, Petrus J.M.; Boller, Klaus J.; Strooisma, A.; Kang, Heung-Sik; Kim, Dong Eon; Schaa, Volker R.W.


    In a photonic free-electron laser electrons are transmitted through a photonic crystal in the form of one or multiple electron beams to generate coherent Cerenkov radiation. Here we consider a photonic-crystal slab consisting of a two-dimensional, periodic array of bars inside a rectangular waveguid

  20. Semiconductor statistics

    CERN Document Server

    Blakemore, J S


    In-depth exploration of the implications of carrier populations and Fermi energies examines distribution of electrons in energy bands and impurity levels of semiconductors. Also: kinetics of semiconductors containing excess carriers, particularly in terms of trapping, excitation, and recombination.

  1. Orientation-free and differentially pumped addition of a low-flux reactive gas beam to a surface analysis system (United States)

    Harthcock, Colin; Jahanbekam, Abdolreza; Eskelsen, Jeremy R.; Lee, David Y.


    We describe an example of a piecewise gas chamber that can be customized to incorporate a low flux of gas-phase radicals with an existing surface analysis chamber for in situ and stepwise gas-surface interaction experiments without any constraint in orientation. The piecewise nature of this gas chamber provides complete angular freedom and easy alignment and does not require any modification of the existing surface analysis chamber. In addition, the entire gas-surface system is readily differentially pumped with the surface chamber kept under ultra-high-vacuum during the gas-surface measurements. This new design also allows not only straightforward reconstruction to accommodate the orientation of different surface chambers but also for the addition of other desired features, such as an additional pump to the current configuration. Stepwise interaction between atomic oxygen and a highly ordered pyrolytic graphite surface was chosen to test the effectiveness of this design, and the site-dependent O-atom chemisorption and clustering on the graphite surface were resolved by a scanning tunneling microscope in the nm-scale. X-ray photoelectron spectroscopy was used to further confirm the identity of the chemisorbed species on the graphite surface as oxygen.

  2. The optical pumping of alkali atoms using coherent radiation from semi-conductor injection lasers and incoherent radiation from resonance lamps (United States)

    Singh, G.


    An experimental study for creating population differences in the ground states of alkali atoms (Cesium 133) is presented. Studies made on GaAs-junction lasers and the achievement of population inversions among the hyperfine levels in the ground state of Cs 133 by optically pumping it with radiation from a GaAs diode laser. Laser output was used to monitor the populations in the ground state hyperfine levels as well as to perform the hyperfine pumping. A GaAs laser operated at about 77 K was used to scan the 8521 A line of Cs 133. Experiments were performed both with neon-filled and with paraflint-coated cells containing the cesium vapor. Investigations were also made for the development of the triple resonance coherent pulse technique and for the detection of microwave induced hyperfine trasistions by destroying the phase relationships produced by a radio frequency pulse. A pulsed cesium resonance lamp developed, and the lamp showed clean and reproducible switching characteristics.

  3. SEMICONDUCTOR INTEGRATED CIRCUITS: An asymmetric MOSFET-C band-pass filter with on-chip charge pump auto-tuning (United States)

    Fangxiong, Chen; Min, Lin; Heping, Ma; Hailong, Jia; Yin, Shi; Forster, Dai


    An asymmetric MOSFET-C band-pass filter (BPF) with on chip charge pump auto-tuning is presented. It is implemented in UMC (United Manufacturing Corporation) 0.18 μm CMOS process technology. The filter system with auto-tuning uses a master-slave technique for continuous tuning in which the charge pump outputs 2.663 V, much higher than the power supply voltage, to improve the linearity of the filter. The main filter with third order low-pass and second order high-pass properties is an asymmetric band-pass filter with bandwidth of 2.730-5.340 MHz. The in-band third order harmonic input intercept point (IIP3) is 16.621 dBm, with 50 Ω as the source impedance. The input referred noise is about 47.455 μVrms. The main filter dissipates 3.528 mW while the auto-tuning system dissipates 2.412 mW from a 1.8 V power supply. The filter with the auto-tuning system occupies 0.592 mm2 and it can be utilized in GPS (global positioning system) and Bluetooth systems.

  4. Stable mode-locked operation of a low repetition rate diode-pumped Nd:GdVO4 laser by combining quadratic polarisation switching and a semiconductor saturable absorber mirror. (United States)

    Gerhard, Christoph; Druon, Frédéric; Georges, Patrick; Couderc, Vincent; Leproux, Philippe


    In this paper, we present the mode-locked operation of an ultra-robustly stabilised Nd:GdVO(4) laser with low repetition rate by combining quadratic polarisation switching and a semiconductor saturable absorber mirror (SESAM). In addition, similar experiment was also done with Nd:YVO(4). For Nd:GdVO(4), 16-ps pulses at 1063 nm with a repetition rate of 3.95 MHz have been obtained for a laser average output power of 1.4 W. For Nd:YVO(4), the performance was 2.5 W of average power for 15-ps pulses at 1064 nm. Moreover, we demonstrate experimentally the advantage of combining these two passive mode locking techniques in terms of stability ranges. We show how the dual mode-locking technique is crucial to obtain a stable and long-term mode-locked regime in our case of a diode-pumped Nd:GdVO(4) laser operating at low repetition rate and more generally how this dual mode-locking technique improves the stability range of the mode-locked operation giving more flexibility on different parameters.

  5. Spectral Feature Analysis of Semiconductor Thin Disk Laser

    Institute of Scientific and Technical Information of China (English)


    The semiconductor thin disk laser is a new type of semiconductor laser. This work gives the basic operation function of the semiconductor disk laser, and analyses the heat effect by the experimentally measured photoluminescence spectrum of the laser chip at different pump power and different temperatures. We can see that: with increasing pump power, the thermal effect of the gain material becomes seriously and causes the saturation of carrier lifetime, so the electron-hole pair created in the absorbtion lay...

  6. A variable frequency semiconductor laser

    Energy Technology Data Exchange (ETDEWEB)

    Tosikhiro, F.; Khiromoto, S.


    A variable frequency, power stabilized semiconductor laser is patented. This laser includes, in addition to an active layer, a photoconducting channel layer and a layer made from a material manifesting a Pockels effect. A voltage is injected between these two layers to vary the emission frequency. The laser pumping voltage is stabilized.

  7. Efficacy of pumping manipulation treatment for closed lock of the temporomandibular joint disorder. Correlation between arthrographic findings using limited cone beam X-ray CT for dental use and mouth opening distance in 20 cases

    Energy Technology Data Exchange (ETDEWEB)

    Honda, Kazuya; Uehara, Tamotsu; Arai, Yoshinori; Kashima, Masahiro; Tsukimura, Naoki; Honda, Masahiko; Iwai, Kazuo; Terakado, Masaaki; Shinoda, Koji [Nihon Univ., Tokyo (Japan). School of Dentistry


    A study was conducted to evaluate the efficacy of pumping manipulation treatment for closed lock of the temporomandibular joint (TMJ) disorder using limited cone beam X-ray CT for dental use. The subjects were 20 patients with TMJ closed lock. Arthrography and pumping manipulation treatment were performed, and the correlation between maximal mouth opening and arthrographic findings was examined. Arthrography showed 16 cases of anterior disk displacement, and 4 cases of sideways displacement. Disk configuration showed 15 abnormal cases and 3 cases of disk perforation. Before treatment, mouth opening distance was 24.2 mm and 1 week after treatment it was 34.4 mm. After 3 months this had improved significantly to 41.0 mm. Comparison of mouth opening distance with arthrographic findings showed that disk perforation was significantly different after 3 months. These results suggest that pumping manipulation treatment might be useful in patients with TMJ closed lock without internal derangement or disk perforation. (author)

  8. Velocity selective optical pumping


    Aminoff, C. G.; Pinard, M.


    We consider optical pumping with a quasi monochromatic tunable light beam, in the low intensity limit where a rate equation regime is obtained The velocity selective optical pumping (V.S.O.P.) introduces a correlation between atomic velocity and internal variables in the ground (or metastable) state. The aim of this article is to evaluate these atomic observables (orientation, alignment, population) as a function of velocity, using a phenomenological description of the relaxation effect of co...

  9. High performance wafer-fused semiconductor disk lasers emitting in the 1300 nm waveband. (United States)

    Sirbu, Alexei; Rantamäki, Antti; Saarinen, Esa J; Iakovlev, Vladimir; Mereuta, Alexandru; Lyytikäinen, Jari; Caliman, Andrei; Volet, Nicolas; Okhotnikov, Oleg G; Kapon, Eli


    We report for the first time on the performance of 1300 nm waveband semiconductor disc lasers (SDLs) with wafer fused gain mirrors that implement intracavity diamond and flip-chip heat dissipation schemes based on the same gain material. With a new type of gain mirror structure, maximum output power values reach 7.1 W with intracavity diamond gain mirrors and 5.6 W with flip-chip gain mirrors, using a pump spot diameter of 300 µm, exhibiting a beam quality factor M(2)< 1.25 in the full operation range. These results confirm previously published theoretical modeling of these types of SDLs.

  10. An excitation method for a semiconductor laser and a power supply

    Energy Technology Data Exchange (ETDEWEB)

    Kadzunari, O.; Katsu, K.


    A method is patented for stabilizing the peak pulsed output power from a semiconductor laser. This method is based on using a feedback circuit. A portion of the lasting beam is recorded by a photodetector; the output signal for this photodetector is amplified by an operational amplifier and is integrated by an RC network. The voltage obtained is compared to a reference voltage and a corresponding voltage is fed to a transistor in the power supply circuit. The pumping current of the laser is modulated by a pulse from a second transistor controlled by the pulse generator.

  11. Ultracold ordered electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Habs, D.; Kramp, J.; Krause, P.; Matl, K.; Neumann, R.; Schwalm, D.


    We have started an experimental program to develop an ultracold electron beam, which can be used together with a standard electron cooling device in the Heidelberg Test Storage Ring TSR. In contrast to the standard-type design using electron beam extraction beam extraction from a heated cathode, the ultracold beam is produced by photoemission of electrons from a cooled semiconductor crystal irradiated with an intense near-infrared laser light beam. Adiabatic acceleration is expected to provide ordering of the electron beam itself. Besides the cooling of ion beams to extremely low temperatures, with the aim of obtaining crystallization, the ultracold beam will constitute an excellent target for atomic physics experiments.

  12. Growth of polar and non-polar nitride semiconductor quasi-substrates by hydride vapor phase epitaxy for the development of optoelectronic devices by molecular beam epitaxy (United States)

    Moldawer, Adam Lyle

    The family of nitride semiconductors has had a profound influence on the development of optoelectronics for a large variety of applications. However, as of yet there are no native substrates commercially available that are grown by liquid phase methods as with Si and GaAs. As a result, the majority of electronic and optoelectronic devices are grown heteroepitaxially on sapphire and SiC. This PhD research addresses both the development of polar and non-polar GaN and AIN templates by Hydride Vapor Phase Epitaxy (HVPE) on sapphire and SiC substrates, as well as the growth and characterization of optoelectronic devices on these templates by molecular beam epitaxy (MBE). Polar and non-polar GaN templates have been grown in a vertical HVPE reactor on the C- and R-planes of sapphire respectively. The growth conditions have been optimized to allow the formation for thick (50um) GaN templates without cracks. These templates were characterized structurally by studying their surface morphologies by SEM and AFM, and their structure through XRD and TEM. The polar C-plane GaN templates were found to be atomically smooth. However, the surface morphology of the non-polar GaN films grown on the R-plane of sapphire were found to have a facetted surface morphology, with the facets intersecting at 120° angles. This surface morphology reflects an equilibrium growth, since the A-plane of GaN grows faster than the M-planes of GaN due to the lower atomic density of the plane. For the development of deep-UV optoelectronics, it is required to grow AIGaN quantum wells on AIN templates. However, since AIN is a high melting point material, such templates have to be grown at higher temperatures, close to half the melting point of the material (1500 °C). As these temperatures cannot be easily obtained by traditional furnace heating, an HVPE reactor has been designed to heat the substrate inductively to these temperatures. This apparatus has been used to grow high-quality, transparent AIN films

  13. Semiconductor spintronics

    CERN Document Server

    Xia, Jianbai; Chang, Kai


    Semiconductor Spintronics, as an emerging research discipline and an important advanced field in physics, has developed quickly and obtained fruitful results in recent decades. This volume is the first monograph summarizing the physical foundation and the experimental results obtained in this field. With the culmination of the authors' extensive working experiences, this book presents the developing history of semiconductor spintronics, its basic concepts and theories, experimental results, and the prospected future development. This unique book intends to provide a systematic and modern foundation for semiconductor spintronics aimed at researchers, professors, post-doctorates, and graduate students, and to help them master the overall knowledge of spintronics.

  14. Semiconductor heterojunctions

    CERN Document Server

    Sharma, B L


    Semiconductor Heterojunctions investigates various aspects of semiconductor heterojunctions. Topics covered include the theory of heterojunctions and their energy band profiles, electrical and optoelectronic properties, and methods of preparation. A number of heterojunction devices are also considered, from photovoltaic converters to photodiodes, transistors, and injection lasers.Comprised of eight chapters, this volume begins with an overview of the theory of heterojunctions and a discussion on abrupt isotype and anisotype heterojunctions, along with graded heterojunctions. The reader is then

  15. Materials for diode pumped solid state lasers (United States)

    Chase, L. L.; Davis, L. E.; Krupke, W. F.; Payne, S. A.


    The advantages of semiconductor diode lasers and laser arrays as pump sources for solid state lasers are reviewed. The properties that are desirable in solid state laser media for various diode pumping applications are discussed, and the characteristics of several promising media are summarized.

  16. Towards filament free semiconductor lasers

    DEFF Research Database (Denmark)

    McInerney, John; O'Brien, Peter; Skovgaard, Peter M. W.


    We outline physical models and simulations for suppression of self-focusing and filamentation in large aperture semiconductor lasers. The principal technical objective is to generate multi-watt CW or quasi-CW outputs with nearly diffraction limited beams, suitable for long distance free space...... propagation structures in lasers and amplifiers which suppress lateral reflections....

  17. Optoelectronic Devices Based on Novel Semiconductor Structures (United States)


    generation are the Nd:YAG beam at 1.0642 ptm and the idler beam from a master oscillator/power oscillator ( MOPO ) pumped by a frequency-tripled Nd:YAG...matched DFG (see Fig. a 72 1). In order to achieve phase-matching, the 1.0642-ptm pump beam and idler beam from the MOPO system are ordinary and...frequency for the MOPO beam (idler), which is given by Avi (1) 4L [no) , (o) ] where n,(,o°) and n(0°) are the indices of refraction for the ordinary

  18. 80-W cw TEM{sub 00} IR beam generation by use of a laser-diode-side-pumped Nd:YAG rod laser

    Energy Technology Data Exchange (ETDEWEB)

    Konno, Susumu; Fujikawa, Shuichi; Yasui, Koji [Mitsubishi Electric Corp. Amagasaki, Hyogo (Japan). Advanced Technology R and D Center


    We have demonstrated high-efficient and high-power operation of a diode-side-pumped Nd:YAG rod laser. The laser has a simple and scalable configuration consisting of a diffusive pumping reflector and an advanced cavity configuration for polarization-dependent bifocusing compensation. (author)

  19. Ultracold Ordered Electron Beam (United States)

    Habs, D.; Kramp, J.; Krause, P.; Matl, K.; Neumann, R.; Schwalm, D.


    We have started an experimental program to develop an ultracold electron beam, which can be used together with a standard electron cooling device in the Heidelberg Test Storage Ring TSR. In contrast to the standard-type design using electron beam extraction from a heated cathode, the ultracold beam is produced by photoemission of electrons from a cooled semiconductor crystal irradiated with an intense near-infrared laser light beam. Adiabatic acceleration is expected to provide ordering of the electron beam itself. Besides the cooling of ion beams to extremely low temperatures, with the aim of obtaining crystallization, the ultracold beam will constitute an excellent target for atomic physics experiments.

  20. Centrifugal pumps

    CERN Document Server

    Anderson, HH


    Centrifugal Pumps describes the whole range of the centrifugal pump (mixed flow and axial flow pumps are dealt with more briefly), with emphasis on the development of the boiler feed pump. Organized into 46 chapters, this book discusses the general hydrodynamic principles, performance, dimensions, type number, flow, and efficiency of centrifugal pumps. This text also explains the pumps performance; entry conditions and cavitation; speed and dimensions for a given duty; and losses. Some chapters further describe centrifugal pump mechanical design, installation, monitoring, and maintenance. The

  1. Experimental study on the characteristics of semiconductor opening switch

    CERN Document Server

    Su Jian Cang; Ding Yong Zhong; Song Zhi Min; Ding Zhen Jie; Liu Guo Zhi


    An experimental set-up is developed to measure the characteristics of semiconductor opening switch (SOS). The parameters, such as interruption impedance, current int eruption time, voltage gain, pulse duration and energy transfer efficiency, are studied experimentally. The experimental results show that forward pumping time and reverse pumping time are important parameters for semiconductor opening switches. The influences of forward pumping time and reverse pumping time on interruption time, voltage gain, and energy transfer efficiency are obtained. In the interruption process, the impedance variation is divided into three phases: that is rapid increasing phase, slow change phase and completely interruption phase

  2. Eccentric Pumping Unit: Cost-effective and Reliable

    Institute of Scientific and Technical Information of China (English)

    Zhang Shaobo; Gao Heping; Chen Yibao; Shi Linsong; Zhang Huiwen


    @@ The beam-type pumping unit is the most widely used ty pe of pumping unit because of its simple geometry and its reliability. However. when its stroke exceeds five meters, the structure of the unit becomes massive and its cost becomes quite high. In order to make full use of the advantages of the beam pumping unit and to enhance its stroke. a new type of pumping unit - the ECCENTRIC PUMPING UNIT - has been designed after two years of the research work.

  3. Pumping life

    DEFF Research Database (Denmark)

    Sitsel, Oleg; Dach, Ingrid; Hoffmann, Robert Daniel


    of membrane proteins: P-type ATPase pumps. This article takes the reader on a tour from Aarhus to Copenhagen, from bacteria to plants and humans, and from ions over protein structures to diseases caused by malfunctioning pump proteins. The magazine Nature once titled work published from PUMPKIN ‘Pumping ions......’. Here we illustrate that the pumping of ions means nothing less than the pumping of life....

  4. Semiconductor diode characterization for total skin electron irradiation. (United States)

    Madrid González, O A; Rivera Montalvo, T


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

  5. Simulation of Sliding Efficiency for Belt Driving in Beam Pumping Units%游梁式抽油机井皮带滑动效率的仿真研究

    Institute of Scientific and Technical Information of China (English)

    邢明明; 董世民


    针对游梁式抽油机皮带传动装置负载扭矩波动大的特点,研究了游梁式抽油机皮带的纵向振动特性、皮带与带轮之间的相对滑动速度以及皮带传动的瞬时滑动效率.将皮带简化为纵向振动的弹性体,建立了皮带在交变摩擦力激励下的纵向振动力学模型与波动方程形式的数学模型;应用振型叠加法建立了皮带纵向振动的数值仿真模型;建立了皮带相对于带轮的瞬时滑动速度、瞬时滑动效率的仿真模型;仿真分析了抽油机曲柄扭矩波动幅值、皮带预紧力对皮带滑动效率的影响.仿真结果表明:抽油机曲柄扭矩波动会降低滑动效率;当抽油机曲柄扭矩存在负扭矩时,皮带滑动效率明显降低;在预紧力能保证皮带传动正常工作的情况下,再增加皮带预紧力会增大皮带的传动效率.%Considering great fluctuation of load torque of the belt driving device in a beam pumping unit,belt longitudinal vibration of beam pumping unit,the relative sliding speed between belt and pulley and instantaneous sliding efficiency were researched. The belt was simplified to elastic body of longitudinal vibration,the mechanical model of longitudinal vibration of the belt which was excited by alternating friction was established,and the mathematical model of the wave equation form was built. The numerical simulation model of wave equation was established with the superposition method of vibration mode. Simulation model of belt instantaneous sliding speed relative to pulley and simulation model of belt instantaneous sliding efficiency were established. The factors of affecting sliding efficiency were pointed out, such as oscillation amplitude of alternating torque and initial tension of belt in beam pumping unit. The following conclusions are obtained by the simulation results:load torque fluctuations of beam pumping unit will lead to lower sliding efficiency;sliding efficiency of belt driving

  6. Oxide semiconductors

    CERN Document Server

    Svensson, Bengt G; Jagadish, Chennupati


    Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. Originally widely known as the ""Willardson and Beer"" Series, it has succeeded in publishing numerous landmark volumes and chapters. The series publishes timely, highly relevant volumes intended for long-term impact and reflecting the truly interdisciplinary nature of the field. The volumes in Semiconductors and Semimetals have been and will continue to be of great interest to physicists, chemists, materials scientists, and device engineers in academia, scient

  7. Semiconductor electrochemistry

    CERN Document Server

    Memming, Rüdiger


    Providing both an introduction and an up-to-date survey of the entire field, this text captivates the reader with its clear style and inspiring, yet solid presentation. The significantly expanded second edition of this milestone work is supplemented by a completely new chapter on the hot topic of nanoparticles and includes the latest insights into the deposition of dye layers on semiconductor electrodes. In his monograph, the acknowledged expert Professor Memming primarily addresses physical and electrochemists, but materials scientists, physicists, and engineers dealing with semiconductor technology and its applications will also benefit greatly from the contents.

  8. Semiconductor statistics

    CERN Document Server

    Blakemore, J S


    Semiconductor Statistics presents statistics aimed at complementing existing books on the relationships between carrier densities and transport effects. The book is divided into two parts. Part I provides introductory material on the electron theory of solids, and then discusses carrier statistics for semiconductors in thermal equilibrium. Of course a solid cannot be in true thermodynamic equilibrium if any electrical current is passed; but when currents are reasonably small the distribution function is but little perturbed, and the carrier distribution for such a """"quasi-equilibrium"""" co

  9. Molecular beam epitaxy

    CERN Document Server

    Pamplin, Brian R


    Molecular Beam Epitaxy introduces the reader to the use of molecular beam epitaxy (MBE) in the generation of III-V and IV-VI compounds and alloys and describes the semiconductor and integrated optics reasons for using the technique. Topics covered include semiconductor superlattices by MBE; design considerations for MBE systems; periodic doping structure in gallium arsenide (GaAs); nonstoichiometry and carrier concentration control in MBE of compound semiconductors; and MBE techniques for IV-VI optoelectronic devices. The use of MBE to fabricate integrated optical devices and to study semicond

  10. A 1.5-W frequency doubled semiconductor disk laser tunable over 40 nm at around 745 nm (United States)

    Saarinen, Esa J.; Lyytikäinen, Jari; Ranta, Sanna; Rantamäki, Antti; Saarela, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Okhotnikov, Oleg G.


    We report on a semiconductor disk laser emitting 1.5 W of output power at the wavelength of 745 nm via intracavity frequency doubling. The high power level and the pumped with commercial low-cost 980 nm laser diode modules. Laser emission at 1490 nm was frequency-doubled with a bismuth borate crystal that was cut for type I critical phase matching. At the maximum output power, we achieved an optical-to-optical efficiency of 8.3% with beam quality parameter M2 below 1.5. The laser wavelength could be tuned with an intracavity birefringent plate from 720 to 764 nm.

  11. Spontaneous generation of vortex and coherent vector beams from a thin-slice c-cut Nd:GdVO4 laser with wide-aperture laser-diode end pumping: application to highly sensitive rotational and translational Doppler velocimetry (United States)

    Otsuka, Kenju; Chu, Shu-Chun


    Selective excitation of Laguerre-Gauss modes (optical vortices: helical LG0,2 and LG0,1), reflecting their weak transverse cross-saturation of population inversions against a preceding higher-order Ince-Gauss (IG0,2) or Hermite-Gauss (HG2,1) mode, was observed in a thin-slice c-cut Nd:GdVO4 laser with wide-aperture laser-diode end pumping. Single-frequency coherent vector beams were generated through the transverse mode locking of a pair of orthogonally polarized IG2,0 and LG0,2 or HG2,1 and LG0,1 modes. Highly sensitive self-mixing rotational and translational Doppler velocimetry is demonstrated by using vortex and coherent vector beams.

  12. Semiconductors and semimetals epitaxial microstructures

    CERN Document Server

    Willardson, Robert K; Beer, Albert C; Gossard, Arthur C


    Newly developed semiconductor microstructures can now guide light and electrons resulting in important consequences for state-of-the-art electronic and photonic devices. This volume introduces a new generation of epitaxial microstructures. Special emphasis has been given to atomic control during growth and the interrelationship between the atomic arrangements and the properties of the structures.Key Features* Atomic-level control of semiconductor microstructures* Molecular beam epitaxy, metal-organic chemical vapor deposition* Quantum wells and quantum wires* Lasers, photon(IR)detectors, heterostructure transistors

  13. Method and system for powering and cooling semiconductor lasers (United States)

    Telford, Steven J; Ladran, Anthony S


    A semiconductor laser system includes a diode laser tile. The diode laser tile includes a mounting fixture having a first side and a second side opposing the first side and an array of semiconductor laser pumps coupled to the first side of the mounting fixture. The semiconductor laser system also includes an electrical pulse generator thermally coupled to the diode bar and a cooling member thermally coupled to the diode bar and the electrical pulse generator.

  14. Magnetocaloric pump (United States)

    Brown, G. V.


    Very cold liquids and gases such as helium, neon, and nitrogen can be pumped by using magnetocaloric effect. Adiabatic magnetization and demagnetization are used to alternately heat and cool slug of pumped fluid contained in closed chamber.

  15. Semiconductor Detectors; Detectores de Semiconductores

    Energy Technology Data Exchange (ETDEWEB)

    Cortina, E.


    Particle detectors based on semiconductor materials are among the few devices used for particle detection that are available to the public at large. In fact we are surrounded by them in our daily lives: they are used in photoelectric cells for opening doors, in digital photographic and video camera, and in bar code readers at supermarket cash registers. (Author)

  16. Pulsed differential pumping system

    Energy Technology Data Exchange (ETDEWEB)

    Antipov, G.N.; Bagautdinov, F.A.; Rybalov, S.V.


    A pulsed differential pumping system is described for extracting an electron beam from a shaping region at a pressure of 10/sup -5/ torr into a volume with a pressure of 10-100 torr. A fast valve is used with appropriate geometrical parameters to reduce the length of the outlet channel considerable while increasing its diameter. Test results are given. The pumping system has two sections which communicate one with the other and with the volume at the elevated pressure which is produced by gasdynamic nozzles.

  17. Heat pumps

    CERN Document Server

    Macmichael, DBA


    A fully revised and extended account of the design, manufacture and use of heat pumps in both industrial and domestic applications. Topics covered include a detailed description of the various heat pump cycles, the components of a heat pump system - drive, compressor, heat exchangers etc., and the more practical considerations to be taken into account in their selection.

  18. Laser micromachining of semiconductors for photonics applications (United States)

    Nantel, Marc; Yashkir, Yuri; Lee, Seong K.; Mugford, Chas; Hockley, Bernard S.


    For decades, precisely machining silicon has been critical for the success of the semiconductor industry. This has traditionally been done through wet chemical etching, but in the pursuit of integrating photonics devices on a single chip, other techniques are worth exploring. This quest opens up interest in finding a non-wet, non-contact, arbitrary-shape milling technique for silicon. In this paper, we present our latest work in the laser micromachining of silicon. A kilohertz-repetition-rate diode-pumped Nd:YLF laser (in infrared, green or ultraviolet modes) is focused on the surface of silicon wafers in a chlorine atmosphere for an enhanced magnitude and control of the etching rate. In the chlorine atmosphere, much less debris is deposited on the surface around the cut, sub-damage threshold machining is achieved for a better control of the etching depth, and etching rates ranging from 20-300,000 micron-cube/s have been measured. In particular, the use of an infrared laser beam is singled out, along with the advantages that it holds. Results of simulations highlight the particular characteristics of the various wavelength chosen for the machining.

  19. Semiconductor nanowire lasers (United States)

    Eaton, Samuel W.; Fu, Anthony; Wong, Andrew B.; Ning, Cun-Zheng; Yang, Peidong


    The discovery and continued development of the laser has revolutionized both science and industry. The advent of miniaturized, semiconductor lasers has made this technology an integral part of everyday life. Exciting research continues with a new focus on nanowire lasers because of their great potential in the field of optoelectronics. In this Review, we explore the latest advancements in the development of nanowire lasers and offer our perspective on future improvements and trends. We discuss fundamental material considerations and the latest, most effective materials for nanowire lasers. A discussion of novel cavity designs and amplification methods is followed by some of the latest work on surface plasmon polariton nanowire lasers. Finally, exciting new reports of electrically pumped nanowire lasers with the potential for integrated optoelectronic applications are described.

  20. Semiconductor Optics

    CERN Document Server

    Klingshirn, Claus F


    This updated and enlarged new edition of Semiconductor Optics provides an introduction to and an overview of semiconductor optics from the IR through the visible to the UV, including linear and nonlinear optical properties, dynamics, magneto and electrooptics, high-excitation effects and laser processes, some applications, experimental techniques and group theory. The mathematics is kept as elementary as possible, sufficient for an intuitive understanding of the experimental results and techniques treated. The subjects covered extend from physics to materials science and optoelectronics. Significantly updated chapters add coverage of current topics such as electron hole plasma, Bose condensation of excitons and meta materials. Over 120 problems, chapter introductions and a detailed index make it the key textbook for graduate students in physics. The mathematics is kept as elementary as possible, sufficient for an intuitive understanding of the experimental results and techniques treated. The subjects covered ...

  1. Semiconductor sensors

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, Frank, E-mail: frank.hartmann@cern.c [Institut fuer Experimentelle Kernphysik, KIT, Wolfgang-Gaede-Str. 1, Karlsruhe 76131 (Germany)


    Semiconductor sensors have been around since the 1950s and today, every high energy physics experiment has one in its repertoire. In Lepton as well as Hadron colliders, silicon vertex and tracking detectors led to the most amazing physics and will continue doing so in the future. This contribution tries to depict the history of these devices exemplarily without being able to honor all important developments and installations. The current understanding of radiation damage mechanisms and recent R and D topics demonstrating the future challenges and possible technical solutions for the SLHC detectors are presented. Consequently semiconductor sensor candidates for an LHC upgrade and a future linear collider are also briefly introduced. The work presented here is a collage of the work of many individual silicon experts spread over several collaborations across the world.

  2. Heat pumps

    CERN Document Server

    Brodowicz, Kazimierz; Wyszynski, M L; Wyszynski


    Heat pumps and related technology are in widespread use in industrial processes and installations. This book presents a unified, comprehensive and systematic treatment of the design and operation of both compression and sorption heat pumps. Heat pump thermodynamics, the choice of working fluid and the characteristics of low temperature heat sources and their application to heat pumps are covered in detail.Economic aspects are discussed and the extensive use of the exergy concept in evaluating performance of heat pumps is a unique feature of the book. The thermodynamic and chemical properties o

  3. Ⅲ-V族三元化合物半导体材料分子束外延的生长热力学%Thermodynamic analysis of growth of ternary III-V semiconductor materials by molecular-beam epitaxy

    Institute of Scientific and Technical Information of China (English)

    叶志成; 舒永春; 曹雪; 龚亮; 皮彪; 姚江宏; 邢晓东; 许京军


    Thermodynamic models for molecular-beam epitaxy (MBE) growth of ternary Ⅲ-V semiconductor materials are proposed. These models are in agreement with our experimental materials InGaP/GaAs and InGaAs/InP, and reported GaAsP/GaAs and InAsP/InP in thermodynamic growth. The lattice strain energy ΔG and thermal decomposition sensitive to growth temperature are demonstrated in the models simultaneously. ΔG is the function of the alloy composition, which is affected by flux ratio and growth temperature directly. The calculation results reveal that flux ratio and growth temperature mainly influence the growth process. Thermodynamic model of quaternary InGaAsP/GaAs semiconductor material is discussed also.%建立Ⅲ-V族三元化合物半导体材料的分子束外延生长热力学模型.该模型与实验材料InGaP/GaAs, InGaAs/InP 及已发表的GaAsP/GaAs, InAsP/InP 的数据吻合得很好.将晶格应变能ΔG及脱附对温度敏感这两个因素同时纳入热力学模型中,束流和生长温度直接影响合金组分,晶格应变能是合金组分的函数.热力学模型计算结果反映了束流和生长温度是生长过程中最主要的影响因素.讨论和分析了四元半导体材料InGaAsP/GaAs的热力学生长模型.

  4. 101 W of average green beam from diode-side-pumped Nd:YAG/LBO-based system in a relay imaged cavity

    Indian Academy of Sciences (India)

    S K Sharma; A J Singh; P K Mukhopadhyay; S M Oak


    Studies on intracavity frequency doubling of acousto-optically Q-switched Nd:YAG rod laser using 18 mm long type-II phase-matched LBO crystal in a relay-imaged cavity is reported. A single pump head comprised of Nd:YAG rod, diffusive reflectors and linear array laser diode bars is used. 101 W of average green power at a total diode pumping power of 700 W is obtained corresponding to 14.4% optical-to-optical conversion efficiency. The pulse repetition rate is 30 kHz with an individual pulse duration of 200 ns.

  5. Broadband fast semiconductor saturable absorber. (United States)

    Jacobovitz-Veselka, G R; Kellerm, U; Asom, T


    Kerr lens mode-locked (KLM) solid-state lasers are typically not self-starting. We address this problem by introducing a broadband semiconductor saturable absorber that could be used as a tunable, all-solid-state, passive starting mechanism. We extend the wavelength tunability of a semiconductor saturable absorber to more than 100 nm using a band-gap-engineered low-temperature molecular-beam-epitaxy (MBE)-grown bulk AlGaAs semiconductor saturable absorber in which the absorption edge of the saturable absorber has been artificially broadened by continuously reducing the Al concentration during the MBE growth. We demonstrate its tunability and its feasibility as a starting mechanism for KLM with a picosecond resonant passive mode-locked Ti:sapphire laser. The extension to femtosecond KLM lasers has been discussed previously.

  6. Parametric Raman anti-Stokes laser at 503 nm with phase-matched collinear beam interaction of orthogonally polarized Raman components in calcite under 532 nm 20 ps laser pumping (United States)

    Smetanin, Sergei; Jelínek, Michal; Kubeček, Václav


    Lasers based on stimulated-Raman-scattering process can be used for the frequency-conversion to the wavelengths that are not readily available from solid-state lasers. Parametric Raman lasers allow generation of not only Stokes, but also anti-Stokes components. However, practically all the known crystalline parametric Raman anti-Stokes lasers have very low conversion efficiencies of about 1 % at theoretically predicted values of up to 40 % because of relatively narrow angular tolerance of phase matching in comparison with angular divergence of the interacting beams. In our investigation, to widen the angular tolerance of four-wave mixing and to obtain high conversion efficiency into the antiStokes wave we propose and study a new scheme of the parametric Raman anti-Stokes laser at 503 nm with phasematched collinear beam interaction of orthogonally polarized Raman components in calcite under 532 nm 20 ps laser pumping. We use only one 532-nm laser source to pump the Raman-active calcite crystal oriented at the phase matched angle for orthogonally polarized Raman components four-wave mixing. Additionally, we split the 532-nm laser radiation into the orthogonally polarized components entering to the Raman-active calcite crystal at the certain incidence angles to fulfill the tangential phase matching compensating walk-off of extraordinary waves for collinear beam interaction in the crystal with the widest angular tolerance of four-wave mixing. For the first time the highest 503-nm anti-Stokes conversion efficiency of 30 % close to the theoretical limit of about 40 % at overall optical efficiency of the parametric Raman anti-Stokes generation of up to 3.5 % in calcite is obtained due to realization of tangential phase matching insensitive to the angular mismatch.

  7. International Workshop on Beam Injection Assessment of Defects in Semiconductors Held in Meudon-Bellevue (France) on 18-20 July 1988 (United States)


    Research Office of the U.S.Army Commissariat A l’Energie Atornique - Leti Laboratoire d’’ Electronique et de Physique Appliqu~e Thomson - Laboratoire...imperial College of Science and Technology. LONDON SW7 2BP Abstract - Scanning elect-Dn microscope (SE.M) EBIC (electron beam induced current) and CL...Bologna, Via ’rnerio 46, Bologna ITALY A.Poggi. E.Susi CNR-LAMEL Institute, Via Castagnoll I, Bologna ITALY ABSTRACT Microscopic inhomogeneities in the

  8. High power semiconductor switches in the 12 kV, 50 kA pulse generator of the SPS beam dump kicker system

    CERN Document Server

    Bonthond, J; Faure, P; Vossenberg, Eugène B


    Horizontal deflection of the beam in the dump kicker system of the CERN SPS accelerator is obtained with a series of fast pulsed magnets. The high current pulses of 50 kA per magnet are generated with capacitor discharge type generators which, combined with a resistive free-wheel diode circuit, deliver a critically damped half-sine current with a rise-time of 25 ms. Each generator consists of two 25 kA units, connected in parallel to a magnet via a low inductance transmission line.

  9. Active control of emission directionality of semiconductor microdisk lasers

    CERN Document Server

    Liew, Seng Fatt; Ge, Li; Solomon, Glenn S; Cao, Hui


    We demonstrate lasing mode selection in nearly circular semiconductor microdisks by shaping the spatial profile of optical pump. Despite of strong mode overlap, adaptive pumping suppresses all lasing modes except the targeted one. Due to slight deformation of the cavity shape and boundary roughness, each lasing mode has distinct emission pattern. By selecting different mode to be the dominant lasing mode, we can switch both the lasing frequency and the output direction. Such tunability by external pump after the laser is fabricated enhances the functionality of semiconductor microcavity lasers.

  10. Electronic Properties of Semiconductor Interfaces. (United States)


    AD-A130 745 ELECTRONIC PROPERTIES OF SEMICONDUCTOR INTERFACES(U) /; UNIVERSIDAD AUfONOMA DE MADRID (SPAIN) DEPT DE FISICA DEL ESTADO SOLIDO F FLORES...J.Sfinchez-Dehesa 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK AREA & WORK UNIT NUMBERS Departamento de Fisica del...resistance (Esaki and Chang 1974). A SL which has received a great deal of attention is GaAs- AlxGa Ix as grown by molecular -beam-epitaxy. Several

  11. Centrifugal pumps

    CERN Document Server

    Gülich, Johann Friedrich


    This book gives an unparalleled, up-to-date, in-depth treatment of all kinds of flow phenomena encountered in centrifugal pumps including the complex interactions of fluid flow with vibrations and wear of materials. The scope includes all aspects of hydraulic design, 3D-flow phenomena and partload operation, cavitation, numerical flow calculations, hydraulic forces, pressure pulsations, noise, pump vibrations (notably bearing housing vibration diagnostics and remedies), pipe vibrations, pump characteristics and pump operation, design of intake structures, the effects of highly viscous flows, pumping of gas-liquid mixtures, hydraulic transport of solids, fatigue damage to impellers or diffusers, material selection under the aspects of fatigue, corrosion, erosion-corrosion or hydro-abrasive wear, pump selection, and hydraulic quality criteria. As a novelty, the 3rd ed. brings a fully analytical design method for radial impellers, which eliminates the arbitrary choices inherent to former design procedures. The d...

  12. A method of developing frequency encoded multi-bit optical data comparator using semiconductor optical amplifier (United States)

    Garai, Sisir Kumar


    Optical data comparator is the part and parcel of arithmetic and logical unit of any optical data processor and it is working as a building block in a larger optical circuit, as an optical switch in all optical header processing and optical packet switching based all optical telecommunications system. In this article the author proposes a method of developing an all optical single bit comparator unit and subsequently extending the proposal to develop a n-bit comparator exploiting the nonlinear rotation of the state of polarization of the probe beam in semiconductor optical amplifier (SOA). Here the dataset to be compared are taken in frequency encoded/decoded form throughout the communication. The major advantages of frequency encoding over all other conventional techniques are that as the frequency of any signal is fundamental one so it can preserve its identity throughout the communication of optical signal and minimizes the probability of bit error problem. For frequency routing purpose optical add/drop multiplexer (ADM) is used which not only route the pump beams properly but also to amplify the pump beams efficiently. Switching speed of 'MZI-SOA switch' as well as SOA based switches are very fast with good on-off contrast ratio and as a result it is possible to obtain very fast action of optical data comparator.

  13. Beam-pumping unit production breakdown automatic monitoring system design%游梁式抽油机生产故障自动监测系统设计

    Institute of Scientific and Technical Information of China (English)

    刘广友; 邵惠生; 董超群


    为了实时准确监测游梁式抽油机的生产运行状态,及时对停井及停电等故障进行排查和处理,研发了一套适用于油田生产现场的油井生产故障自动监测系统。系统采用接近开关检测曲柄销的运动状态,采用ACDC模块检测抽油机的供电状态,应用GSM网络将报警信息远传至上位机系统,通过页面开发和网络发布,实现了油井生产运行状态的在线实时监测。现场应用表面,系统停电报警响应时间小于20 s,停井报警响应时间小于60 s,且无误报漏报情况发生,满足现场实时性与准确性要求。%In order to monitor the beam-pumping unit production status accurately and process the breakdown or power failure in time, a production breakdown monitoring system for the beam-pumping unit is researched and developed. The proximity switch is adopted to detect the state of motion of the crank pin. The ACDC module is used to detect the state of power supply. The alarm information is transmitted to the upper computer by GSM network. The pages are developed and published. The online real-time monitoring of running status of the beam-pumping unit is realized. The application result shows that the response time of power failure is less than 20s, the response time of breakdown is less than 60s, and the system meets the real-time and accuracy requirements.

  14. 750 nm 1.5 W frequency-doubled semiconductor disk laser with a 44 nm tuning range. (United States)

    Saarinen, Esa J; Lyytikäinen, Jari; Ranta, Sanna; Rantamäki, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Okhotnikov, Oleg G


    We demonstrate 1.5 W of output power at the wavelength of 750 nm by intracavity frequency doubling a wafer-fused semiconductor disk laser diode-pumped at 980 nm. An optical-to-optical efficiency of 8.3% was achieved using a bismuth borate crystal. The wavelength of the doubled emission could be tuned from 720 to 764 nm with an intracavity birefringent plate. The beam quality parameter M2 of the laser output was measured to be below 1.5 at all pump powers. The laser is a promising tool for biomedical applications that can take advantage of the large penetration depth of light in tissue in the 700-800 nm spectral range.

  15. Power semiconductors

    CERN Document Server

    Kubát, M


    The book contains a summary of our knowledge of power semiconductor structures. It presents first a short historic introduction (Chap. I) as well as a brief selection of facts from solid state physics, in particular those related to power semiconductors (Chap. 2). The book deals with diode structures in Chap. 3. In addition to fundamental facts in pn-junction theory, the book covers mainly the important processes of power structures. It describes the emitter efficiency and function of microleaks (shunts). the p +p and n + n junctions, and in particular the recent theory of the pin, pvn and p1tn junctions, whose role appears to be decisive for the forward mode not only of diode structures but also of more complex ones. For power diode structures the reverse mode is the decisive factor in pn-junction breakdown theory. The presentation given here uses engineering features (the multiplication factor M and the experimentally detected laws for the volume and surface of crystals), which condenses the presentation an...

  16. Magnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bihler, Christoph


    In this thesis we investigated in detail the properties of Ga{sub 1-x}Mn{sub x}As, Ga{sub 1-x}Mn{sub x}P, and Ga{sub 1-x}Mn{sub x}N dilute magnetic semiconductor thin films with a focus on the magnetic anisotropy and the changes of their properties upon hydrogenation. We applied two complementary spectroscopic techniques to address the position of H in magnetic semiconductors: (i) Electron paramagnetic resonance, which provides direct information on the symmetry of the crystal field of the Mn{sup 2+} atoms and (ii) x-ray absorption fine structure analysis which allows to probe the local crystallographic neighborhood of the absorbing Mn atom via analysing the fine structure at the Mn K absorption edge. Finally, we discussed the obstacles that have to be overcome to achieve Curie temperatures above the current maximum in Ga{sub 1-x}Mn{sub x}As of 185 K. Here, we outlined in detail the generic problem of the formation of precipitates at the example of Ge:MN. (orig.)

  17. Dopant profiling of focused ion beam milled semiconductors using off-axis electron holography; reducing artifacts, extending detection limits and reducing the effects of gallium implantation

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, David, E-mail: [CEA, LETI, MINATEC, F38054 Grenoble (France); Ailliot, Cyril; Barnes, Jean-Paul; Hartmann, Jean-Michel [CEA, LETI, MINATEC, F38054 Grenoble (France); Salles, Phillipe; Benassayag, Gerard [CEMES-CNRS, nMat group, 29 rue Jean Marvig, 31055 Toulouse (France); Dunin-Borkowski, Rafal E. [Center for Electron Nanoscopy, Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark)


    Focused ion beam (FIB) milling is one of the few specimen preparation techniques that can be used to prepare parallel-sided specimens with nm-scale site specificity for examination using off-axis electron holography in the transmission electron microscope (TEM). However, FIB milling results in the implantation of Ga, the formation of amorphous surface layers and the introduction of defects deep into the specimens. Here we show that these effects can be reduced by lowering the operating voltage of the FIB and by annealing the specimens at low temperature. We also show that the electrically inactive thickness is dependent on both the operating voltage and type of ion used during FIB milling.

  18. Semiconductor Laser Measurements Laboratory (United States)

    Federal Laboratory Consortium — The Semiconductor Laser Measurements Laboratory is equipped to investigate and characterize the lasing properties of semiconductor diode lasers. Lasing features such...

  19. Electrically Pumped Vertical-Cavity Amplifiers

    DEFF Research Database (Denmark)

    Greibe, Tine


    In this work, the design of electrically pumped vertical cavity semiconductor optical amplifiers (eVCAs) for use in a mode-locked external-cavity laser has been developed, investigated and analysed. Four different eVCAs, one top-emitting and three bottom emitting structures, have been designed...... and discussed. The thesis concludes with recommendations for further work towards the realisation of compact electrically pumped mode-locked vertical externalcavity surface emitting lasers....

  20. Advanced Semiconductor Devices (United States)

    Shur, Michael S.; Maki, Paul A.; Kolodzey, James


    I. Wide band gap devices. Wide-Bandgap Semiconductor devices for automotive applications / M. Sugimoto ... [et al.]. A GaN on SiC HFET device technology for wireless infrastructure applications / B. Green ... [et al.]. Drift velocity limitation in GaN HEMT channels / A. Matulionis. Simulations of field-plated and recessed gate gallium nitride-based heterojunction field-effect transistors / V. O. Turin, M. S. Shur and D. B. Veksler. Low temperature electroluminescence of green and deep green GaInN/GaN light emitting diodes / Y. Li ... [et al.]. Spatial spectral analysis in high brightness GaInN/GaN light emitting diodes / T. Detchprohm ... [et al.]. Self-induced surface texturing of Al2O3 by means of inductively coupled plasma reactive ion etching in Cl2 chemistry / P. Batoni ... [et al.]. Field and termionic field transport in aluminium gallium arsenide heterojunction barriers / D. V. Morgan and A. Porch. Electrical characteristics and carrier lifetime measurements in high voltage 4H-SiC PiN diodes / P. A. Losee ... [et al.]. Geometry and short channel effects on enhancement-mode n-Channel GaN MOSFETs on p and n- GaN/sapphire substrates / W. Huang, T. Khan and T. P. Chow. 4H-SiC Vertical RESURF Schottky Rectifiers and MOSFETs / Y. Wang, P. A. Losee and T. P. Chow. Present status and future Directions of SiGe HBT technology / M. H. Khater ... [et al.]Optical properties of GaInN/GaN multi-quantum Wells structure and light emitting diode grown by metalorganic chemical vapor phase epitaxy / J. Senawiratne ... [et al.]. Electrical comparison of Ta/Ti/Al/Mo/Au and Ti/Al/Mo/Au Ohmic contacts on undoped GaN HEMTs structure with AlN interlayer / Y. Sun and L. F. Eastman. Above 2 A/mm drain current density of GaN HEMTs grown on sapphire / F. Medjdoub ... [et al.]. Focused thermal beam direct patterning on InGaN during molecular beam epitaxy / X. Chen, W. J. Schaff and L. F. Eastman -- II. Terahertz and millimeter wave devices. Temperature-dependent microwave performance of

  1. Semiconductor strain metrology principles and applications

    CERN Document Server

    Wong, Terence KS


    This book surveys the major and newly developed techniques for semiconductor strain metrology. Semiconductor strain metrology has emerged in recent years as a topic of great interest to researchers involved in thin film and nanoscale device characterization. This e-book employs a tutorial approach to explain the principles and applications of each technique specifically tailored for graduate students and postdoctoral researchers. Selected topics include optical, electron beam, ion beam and synchrotron x-ray techniques. Unlike earlier references, this e-book specifically discusses strain metrol

  2. Cryogenic semiconductor high-intensity radiation monitors

    CERN Document Server

    Palmieri, V G; Borer, K; Casagrande, L; Da Vià, C; Devine, S R H; Dezillie, B; Esposito, A; Granata, V; Hauler, F; Jungermann, L; Li, Z; Lourenço, C; Niinikoski, T O; O'Shea, V


    This paper describes a novel technique to monitor high-intensity particle beams by means of a semiconductor detector. It consists of cooling a semiconductor detector down to cryogenic temperature to suppress the thermally generated leakage current and to precisely measure the integrated ionization signal. It will be shown that such a device provides very good linearity and a dynamic range wider than is possible with existing techniques. Moreover, thanks to the Lazarus effect, extreme radiation hardness can be achieved providing in turn absolute intensity measurements against precise calibration of the device at low beam flux.

  3. All solid-state 191.7 nm deep-UV light source by seventh harmonic generation of an 888 nm pumped, Q-switched 1342 nm Nd:YVO₄ laser with excellent beam quality. (United States)

    Koch, Peter; Bartschke, Juergen; L'huillier, Johannes A


    In this paper we report on the realization of a deep-UV light source using the 1.3 μm transition of neodymium as pumping wavelength. The 191.7 nm radiation was obtained by generating the seventh harmonic of a high-power Q-switched 1342 nm Nd:YVO4 laser. A cesium lithium borate crystal was used for sum frequency mixing of the sixth harmonic and the fundamental. With a total of four conversion stages, up to 240 mW were achieved, with excellent beam quality at 155 mW (M2 < 1.7) and 190 mW (M2 < 1.9).

  4. Squeezed light in semiconductors

    CERN Document Server

    Ward, M B


    Experimental evidence is presented for the generation of photon-number squeezed states of light as a result of multi-photon absorption. Photon-number squeezing as a result of non-linear absorption has long been predicted and results have been obtained utilising two very different material systems: (i) an AIGaAs waveguide in which high optical intensities can be maintained over a relatively long interaction length of 2 mm; (ii) the organic polymer p-toluene sulphonate polydiacetylene that is essentially a one-dimensional semiconductor possessing a highly nonlinear optical susceptibility. The resulting nonlinear absorption is shown to leave the transmitted light in a state that is clearly nonclassical, exhibiting photon-number fluctuations below the shot-noise limit. Tuning the laser wavelength across the half-bandgap energy has enabled a comparison between two- and three-photon processes in the semiconductor waveguide. The correlations created between different spectral components of a pulsed beam of light as ...

  5. Ferroelectric Pump (United States)

    Jalink, Antony, Jr. (Inventor); Hellbaum, Richard F. (Inventor); Rohrbach, Wayne W. (Inventor)


    A ferroelectric pump has one or more variable volume pumping chambers internal to a housing. Each chamber has at least one wall comprising a dome shaped internally prestressed ferroelectric actuator having a curvature and a dome height that varies with an electric voltage applied between an inside and outside surface of the actuator. A pumped medium flows into and out of each pumping chamber in response to displacement of the ferroelectric actuator. The ferroelectric actuator is mounted within each wall and isolates each ferroelectric actuator from the pumped medium, supplies a path for voltage to be applied to each ferroelectric actuator, and provides for positive containment of each ferroelectric actuator while allowing displacement of the entirety of each ferroelectric actuator in response to the applied voltage.

  6. Transverse and Quantum Effects in Light Control by Light; (A) Parallel Beams: Pump Dynamics for Three Level Superfluorescence; and (B) Counterflow Beams: An Algorithm for Transverse, Full Transient Effects in Optical Bi-Stability in a Fabryperot Cavity. (United States)


    Collaborations: (i) Physics A. Dr. Charles M. Bowden (MICOM) - Two-level amplifier output stabilisation and three-ievel pump dynamics B. Professor Michael a Foucault pendulum. (See Fig. 6b). The SF process is a unique macroscopic manifestation of quantum fluctuations, even though they are proportional...otherwise. (b) No level degeneracy, T2 = T2 =, KL = 0. (c) T2 = m. (d) T2 = . Ce) KL = 0. (f) KL 5. (g) No level degeneracy. Fig. 6b. Foucault pendulum co

  7. Hybrid integration of III-V semiconductor lasers on silicon waveguides using optofluidic microbubble manipulation (United States)

    Jung, Youngho; Shim, Jaeho; Kwon, Kyungmook; You, Jong-Bum; Choi, Kyunghan; Yu, Kyoungsik


    Optofluidic manipulation mechanisms have been successfully applied to micro/nano-scale assembly and handling applications in biophysics, electronics, and photonics. Here, we extend the laser-based optofluidic microbubble manipulation technique to achieve hybrid integration of compound semiconductor microdisk lasers on the silicon photonic circuit platform. The microscale compound semiconductor block trapped on the microbubble surface can be precisely assembled on a desired position using photothermocapillary convective flows induced by focused laser beam illumination. Strong light absorption within the micro-scale compound semiconductor object allows real-time and on-demand microbubble generation. After the assembly process, we verify that electromagnetic radiation from the optically-pumped InGaAsP microdisk laser can be efficiently coupled to the single-mode silicon waveguide through vertical evanescent coupling. Our simple and accurate microbubble-based manipulation technique may provide a new pathway for realizing high precision fluidic assembly schemes for heterogeneously integrated photonic/electronic platforms as well as microelectromechanical systems.

  8. Piston-assisted charge pumping

    CERN Document Server

    Kaur, D; Mourokh, L


    We examine charge transport through a system of three sites connected in series in the situation when an oscillating charged piston modulates the energy of the middle site. We show that with an appropriate set of parameters, charge can be transferred against an applied voltage. In this scenario, when the oscillating piston shifts away from the middle site, the energy of the site decreases and it is populated by a charge transferred from the lower energy site. On the other hand, when the piston returns to close proximity, the energy of the middle site increases and it is depopulated by the higher energy site. Thus through this process, the charge is pumped against the potential gradient. Our results can explain the process of proton pumping in one of the mitochondrial enzymes, Complex I. Moreover, this mechanism can be used for electron pumping in semiconductor nanostructures.

  9. Flash-lamp-pumped picosecond Nd:YAG regenerative amplifier

    Institute of Scientific and Technical Information of China (English)

    Bingyuan Zhang; Gang Li; Meng Chen; Guoju Wang; Yonggang Wang; Xiaoyu Ma


    @@ A flash-lamp-pumped Nd:YAG regenerative amplifier has been developed at 1.06 μm, seeded with 10-ps pulses from a diode-end-pumped and mode-locked Nd:YAG oscillator with homemade semiconductor saturable absorber mirror(SESAM).

  10. Semiconductor laser. Halbleiterlaser

    Energy Technology Data Exchange (ETDEWEB)

    Wuenstel, K.; Gohla, B.; Tegude, F.; Luz, G.; Hildebrand, O.


    A highly modulable semiconductor laser and a process for its manufacture are described. The semiconductor laser has a substrate, a stack of semiconductor layers and electrical contacts. To reduce the capacity, the width of the stack of semiconductor layers is reduced at the sides by anisotropic etching. The electrical contacts are situated on the same side of the substrate and are applied in the same stage of the process. The semiconductor laser is suitable for monolithic integration in other components.

  11. Towards Electrically Pumped Nanolasers for Terabit Communication

    DEFF Research Database (Denmark)

    Lupi, Alexandra

    This thesis deals with modeling, design, fabrication and characterization of vertically electrically pumped photonic crystal light-emitting devices. For this purpose a new material platform of III-V semiconductors on silicon has been developed. The devices fabricated on this platform can be used ...

  12. Penis Pump (United States)

    ... claim that they can be used to increase penis size, but there's no evidence that they work for ... circumstances, using a penis pump might help your penis maintain its natural size and shape after prostate surgery or if you ...

  13. High throughput combinatorial screening of semiconductor materials (United States)

    Mao, Samuel S.


    This article provides an overview of an advanced combinatorial material discovery platform developed recently for screening semiconductor materials with properties that may have applications ranging from radiation detectors to solar cells. Semiconductor thin-film libraries, each consisting of 256 materials of different composition arranged into a 16×16 matrix, were fabricated using laser-assisted evaporation process along with a combinatorial mechanism to achieve variations. The composition and microstructure of individual materials on each thin-film library were characterized with an integrated scanning micro-beam x-ray fluorescence and diffraction system, while the band gaps were determined by scanning optical reflection and transmission of the libraries. An ultrafast ultraviolet photon-induced charge probe was devised to measure the mobility and lifetime of individual thin-film materials on semiconductor libraries. Selected results on the discovery of semiconductors with desired band gaps and transport properties are illustrated.

  14. Modeling of optically controlled reflective bistability in a vertical cavity semiconductor saturable absorber (United States)

    Mishra, L.


    Bistability switching between two optical signals has been studied theoretically utilizing the concept of cross absorption modulation in a vertical cavity semiconductor saturable absorber (VCSSA). The probe beam is fixed at a wavelength other than the low power cavity resonance wavelength, which exhibits bistable characteristic by controlling the power of a pump beam (λpump≠λprobe). The cavity nonlinear effects that arises simultaneously from the excitonic absorption bleaching, and the carrier induced nonlinear index change has been considered in the model. The high power absorption in the active region introduces thermal effects within the nonlinear cavity due to which the effective cavity length changes. This leads to a red-shift of the cavity resonance wavelength, which results a change in phase of the optical fields within the cavity. In the simulation, the phase-change due to this resonance shifting is considered to be constant over time, and it assumes the value corresponding to the maximum input power. Further, an initial phase detuning of the probe beam has been considered to investigate its effect on switching. It is observed from the simulated results that, the output of the probe beam exhibits either clockwise or counter-clockwise bistability, depending on its initial phase detuning.

  15. A semiconductor photon-sorter (United States)

    Bennett, A. J.; Lee, J. P.; Ellis, D. J. P.; Farrer, I.; Ritchie, D. A.; Shields, A. J.


    Obtaining substantial nonlinear effects at the single-photon level is a considerable challenge that holds great potential for quantum optical measurements and information processing. Of the progress that has been made in recent years one of the most promising methods is to scatter coherent light from quantum emitters, imprinting quantum correlations onto the photons. We report effective interactions between photons, controlled by a single semiconductor quantum dot that is weakly coupled to a monolithic cavity. We show that the nonlinearity of a transition modifies the counting statistics of a Poissonian beam, sorting the photons in number. This is used to create strong correlations between detection events and to create polarization-correlated photons from an uncorrelated stream using a single spin. These results pave the way for semiconductor optical switches operated by single quanta of light.

  16. Degenerate four-wave mixing in semiconductor-doped glasses below the absorption edge (United States)

    Bindra, K. S.; Oak, S. M.; Rustagi, K. C.


    We report measurements of degenerate four-wave-mixing reflectivity at a frequency below the band gap of semiconductor-doped glasses in the intensity range 0.5-10 GW/cm2. Up to intensities ~2.5 GW/cm2, the conjugate reflectivity varies like the fourth power of intensity signifying a fifth-order nonlinearity due to band filling by two-photon absorption. Surprisingly, at a higher intensity range the conjugate signal showed a cubic dependence on the pump intensity, which is typical of the χ(3) process. We show that this cubic dependence does not necessarily indicate a third-order process as usually assumed. Instead, it is shown to arise due to a reduction of the effective intensity by nonlinear absorption of the interacting beams.

  17. Evolution of the Novalux extended cavity surface-emitting semiconductor laser (NECSEL) (United States)

    McInerney, John G.


    Novalux Inc was an enterprise founded by Aram Mooradian in 1998 to commercialise a novel electrically pumped vertical extended cavity semiconductor laser platform, initially aiming to produce pump lasers for optical fiber telecommunication networks. Following successful major investment in 2000, the company developed a range of single- and multi-mode 980 nm pump lasers emitting from 100-500 mW with excellent beam quality and efficiency. This rapid development required solution of several significant problems in chip and external cavity design, substrate and DBR mirror optimization, thermal engineering and mode selection. Output coupling to single mode fiber was exceptional. Following the collapse of the long haul telecom market in late 2001, a major reorientation of effort was undertaken, initially to develop compact 60-100 mW hybrid monolithically integrated pumplets for metro/local amplified networks, then to frequency-doubled blue light emitters for biotech, reprographics and general scientific applications. During 2001-3 I worked at Novalux on a career break from University College Cork, first as R&D Director managing a small group tasked with producing new capabilities and product options based on the NECSEL platform, including high power, pulsed and frequency doubled versions, then in 2002 as Director of New Product Realization managing the full engineering team, leading the transition to frequency doubled products.

  18. Thin-disk laser pump schemes for large number of passes and moderate pump source quality (United States)

    Schuhmann, Karsten; Hänsch, Theodor W.; Kirch, Klaus; Knecht, Andreas; Kottmann, Franz; Nez, Francois; Pohl, Randolf; Taqqu, David; Antognini, Aldo


    Novel thin-disk laser pump layouts are proposed yielding an increased number of passes for a given pump module size and pump source quality. These novel layouts result from a general scheme which bases on merging two simpler pump optics arrangements. Some peculiar examples can be realized by adapting standard commercially available pump optics simply by intro ducing an additional mirror-pair. More pump passes yield better efficiency, opening the way for usage of active materials with low absorption. In a standard multi-pass pump design, scaling of the number of beam passes brings ab out an increase of the overall size of the optical arrangement or an increase of the pump source quality requirements. Such increases are minimized in our scheme, making them eligible for industrial applications

  19. Thin-disk laser pump schemes for large number of passes and moderate pump source quality. (United States)

    Schuhmann, Karsten; Hänsch, Theodor W; Kirch, Klaus; Knecht, Andreas; Kottmann, Franz; Nez, Francois; Pohl, Randolf; Taqqu, David; Antognini, Aldo


    Thin-disk laser pump layouts yielding an increased number of passes for a given pump module size and pump source quality are proposed. These layouts result from a general scheme based on merging two simpler pump optics arrangements. Some peculiar examples can be realized by adapting standard, commercially available pump optics with an additional mirror pair. More pump passes yield better efficiency, opening the way for the usage of active materials with low absorption. In a standard multipass pump design, scaling of the number of beam passes brings about an increase in the overall size of the optical arrangement or an increase in the pump source quality requirements. Such increases are minimized in our scheme, making them eligible for industrial applications.

  20. Thin-disk laser pump schemes for large number of passes and moderate pump source quality

    CERN Document Server

    Schuhmann, K; Kirch, K; Knecht, A; Kottmann, F; Nez, F; Pohl, R; Taqqu, D; Antognini, A


    Novel thin-disk laser pump layouts are proposed yielding an increased number of passes for a given pump module size and pump source quality. These novel layouts result from a general scheme which bases on merging two simpler pump optics arrangements. Some peculiar examples can be realized by adapting standard commercially available pump optics simply by intro ducing an additional mirror-pair. More pump passes yield better efficiency, opening the way for usage of active materials with low absorption. In a standard multi-pass pump design, scaling of the number of beam passes brings ab out an increase of the overall size of the optical arrangement or an increase of the pump source quality requirements. Such increases are minimized in our scheme, making them eligible for industrial applications

  1. The Optically Pumped Cs Frequency Standard at the NRLM (United States)


    References 1. J.L. Picqu6, "Hyperfine optical pumping of a cesium atomic beam, and applications," Metrologia, vo1.13, pp.115-119, 1977. 2. M. Arditi and... Arditi , "A caesium beam atomic clock with laser optical pumping, as a potential frequency standard," Metrologia, vo1.18, pp.59-66, 1982. 4. G

  2. Fundamentals of semiconductor devices

    CERN Document Server

    Lindmayer, Joseph


    Semiconductor properties ; semiconductor junctions or diodes ; transistor fundamentals ; inhomogeneous impurity distributions, drift or graded-base transistors ; high-frequency properties of transistors ; band structure of semiconductors ; high current densities and mechanisms of carrier transport ; transistor transient response and recombination processes ; surfaces, field-effect transistors, and composite junctions ; additional semiconductor characteristics ; additional semiconductor devices and microcircuits ; more metal, insulator, and semiconductor combinations for devices ; four-pole parameters and configuration rotation ; four-poles of combined networks and devices ; equivalent circuits ; the error function and its properties ; Fermi-Dirac statistics ; useful physical constants.

  3. Workshop report and presentations from the Semiconductor Research Corporation-DOE Semiconductor Task Force Workshop (United States)

    The Semiconductor Research Corporation-DOE Semiconductor Task Force Workshop was held in Oak ridge, Tennessee, on November 2-3, 1987. It was to provide a forum for representatives of the national laboratories, DOE, and the semiconductor industry in which to discuss capabilities of the national laboratories which could contribute to the future competitiveness of the US semiconductor industry, to identify specific large and small projects at the national laboratories which would be of direct benefit to the semiconductor industry, and to find ways of implementing these projects. Numerous small projects were identified which would utilize unique capabilities of the national laboratories in advanced ion implantation, plasma processing (including electron cyclotron resonance plasmas), ion and cluster beam deposition, materials characterization, electronic packaging, and laser processing and deposition. Five large-scale candidate projects were identified in synchrotron x-ray lithography, silicon process integration, advanced materials processing science, process analysis and diagnostics, and ultra clean room engineering. The major obstacle to implementing these projects if the lack of appropriate funds to initiate and stimulate interactions between the national laboratories and the semiconductor industry. SEMATECH and the federal government are potential sources of seed funds for these projects. The Semiconductor Research Corporation is ideally suited to interface the semiconductor industry and the national laboratories for many of these interactions.

  4. Vertical external cavity surface emitting semiconductor lasers

    CERN Document Server

    Holm, M


    Active stabilisation showed a relative locked linewidth of approx 3 kHz. Coarse tuning over 7 nm was achieved using a 3-plate birefingent filter plate while fine-tuning using cavity length change allowed tuning over 250 MHz. Vertical external cavity semiconductor lasers have emerged as an interesting technology based on current vertical cavity semiconductor laser knowledge. High power output into a single transverse mode has attracted companies requiring good fibre coupling for telecommunications systems. The structure comprises of a grown semiconductor Bragg reflector topped with a multiple quantum well gain region. This is then included in an external cavity. This device is then optically pumped to promote laser action. Theoretical modelling of AIGaAs based VECSEL structures was undertaken, showing the effect of device design on laser characteristics. A simple 3-mirror cavity was constructed to assess the static characteristics of the structure. Up to 153 mW of output power was achieved in a single transver...

  5. Design on Static VAR Generator of Beam Type Water Pump Applied to Coalbed Methane Mining%煤层气开采用游梁式抽水机静止无功发生器设计

    Institute of Scientific and Technical Information of China (English)

    白利军; 王振翀; 庄园; 王聪


    According to the power supply quality problems caused by the low power factor and high harmonic content of power distribution network for the beam type water pump applied to the coalbed methane mining area,a study on three level static VAR compensation technol-ogy was conducted.With an analysis on the causes of VAR and harmonics occurred in the power distribution network,based on diode-clamped three-level inverter,a topological structure of the static VAR generator and the voltage and current double-loop control tactics were designed and the three-level space vector pulse width modulation (SVPWM)tactics were simplified.Meanwhile,test prototype was built and applied to a production site of Lanyan Coal Bed Methane Company,Shanxi Jincheng Anthracite Mining Group.The production practice results showed that three level static VAR generator designed could effectively improve the power factor of power distribution net-work for beam type water pump applied to the coalbed methane mining and could effectively reduce the current harmonic content of the power distribution network,which could improve the power supply quality of the power distribution network.%针对应用于煤层气开采领域的游梁式抽水机配电网功率因数偏低且谐波含量较大导致的供电质量问题,进行了三电平静止无功补偿技术的研究。在分析了配电网无功、谐波产生原因的基础上,设计了基于二极管箝位型三电平逆变器的静止无功发生器拓扑结构和电压电流双闭环控制策略,简化了三电平空间矢量脉宽调制( SVPWM)策略,同时搭建了试验样机并应用于山西晋煤集团蓝焰煤层气公司生产现场。实践结果表明,电网平均功率因素提高到0.99,所设计的三电平静止无功发生器可有效提高游梁式抽水机配电网功率因数,同时有效降低配电网电流谐波含量,从而提高了配电网的供电质量。

  6. Spectroscopy of intraband optical transitions in anisotropic semiconductor nanocrystals (United States)

    Turkov, Vadim K.; Baimuratov, Anvar S.; Rukhlenko, Ivan D.; Baranov, Alexander V.; Fedorov, Anatoly V.


    We propose a new type of optical spectroscopy of anisotropic semiconductor nanocrystals, which is based on the welldeveloped stationary pump-probe technique, where the pump and probe fields are absorbed upon, respectively, interband and intraband transitions of the nanocrystals' electronic subsystem. We develop a general theory of intraband absorption based on the density matrix formalism. This theory can be applied to study degenerate eigenstates of electrons in semiconductor nanocrystals of different shapes and dimentions. We demonstrate that the angular dependence of intraband absorption by nonspherical nanocrystals enables investigating their shape and orientation, as well as the symmetry of quantum states excited by the probe field and selection rules of electronic transitions.

  7. He2 (60-100nm) and Ne_2^* (80-90nm) excimer lamps pumped by low energy electron beams (United States)

    Ulrich, Andreas; Wieser, Jochen; Salvermoser, Manfred; Murnick, Daniel E.


    Low energy (10 to 20keV) electron beams transmitted through extremely thin ceramic foils into high pressure rare gases and rare gas mixtures have been demonstrated to produce efficiently excimer radiation [1,2]. In this report, previous work has been extended to the deep UV emission from helium and neon excimers. The localized nature of the excitation allows windowless systems to be used in a rare gas atmosphere transparent to the 60 to 100nm radiation produced. Both pulsed and cw sources can be realized with extremely high brightness possible. Because of the high energy per photon, such systems may be useful for a variety of materials modification applications. [1] J. Wieser et al. Rev. Sci. Instrum 68, 1360 (1997) [2] M. Salvermoser et al., J. Appl. Phys. 88, 453 (2000) [3] A. Ulrich et al. Physikalische Blätter 56, 49 (2000)

  8. PLT rotating pumped limiter

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, S.A.; Budny, R.V.; Corso, V.; Boychuck, J.; Grisham, L.; Heifetz, D.; Hosea, J.; Luyber, S.; Loprest, P.; Manos, D.


    A limiter with a specially contoured front face and the ability to rotate during tokamak discharges has been installed in a PLT pump duct. These features have been selected to handle the unique particle removal and heat load requirements of ICRF heating and lower-hybrid current-drive experiments. The limiter has been conditioned and commissioned in an ion-beam test stand by irradiation with 1 MW power, 200 ms duration beams of 40 keV hydrogen ions. Operation in PLT during ohmic discharges has proven the ability of the limiter to reduce localized heating caused by energetic electron bombardment and to remove about 2% of the ions lost to the PLT walls and limiters.

  9. Laser cooling in semiconductors (Conference Presentation) (United States)

    Zhang, Jun


    Laser cooling of semiconductor is very important topic in science researches and technological applications. Here we will report our progresses on laser cooling in semiconductors. By using of strong coupling between excitons and longitudinal optical phonons (LOPs), which allows the resonant annihilation of multiple LOPs in luminescence up-conversion processes, we observe a net cooling by about 40 K starting from 290 kelvin with 514-nm pumping and about 15 K starting from100 K with 532-nm pumping in a semiconductor using group-II-VI cadmium sulphide nanobelts. We also discuss the thickness dependence of laser cooing in CdS nanobelts, a concept porotype of semiconductor cryocooler and possibility of laser cooling in II-VI semiconductor family including CdSSe、CdSe, CdSe/ZnTe QDs and bulk CdS et al., Beyond II-VI semiconductor, we will present our recent progress in laser cooling of organic-inorganic perovskite materials, which show a very big cooling power and external quantum efficiency in 3D and 2D case. Further more, we demonstrate a resolved sideband Raman cooling of a specific LO phonon in ZnTe, in which only one specific phonon resonant with exciton can be cooled or heated. In the end, we will discuss the nonlinear anti-Stokes Raman and anti-Stokes photoluminescence upcoversion in very low temperature as low as down to liquid 4.2 K. In this case, the anti-Stokes resonance induces a quadratic power denpendece of anti-Stokes Raman and anti-Stokes PL. We proposed a CARS-like process to explain it. This nonlinear process also provides a possible physics picture of ultra-low temperatures phonon assisted photoluminescence and anti-Stokes Raman process.

  10. Quantum processes in semiconductors

    CERN Document Server

    Ridley, B K


    Aimed at graduate students, this is a guide to quantum processes of importance in the physics and technology of semiconductors. The fifth edition includes new chapters that expand the coverage of semiconductor physics relevant to its accompanying technology.

  11. Compact ultrafast orthogonal acceleration time-of-flight mass spectrometer for on-line gas analysis by electron impact ionization and soft single photon ionization using an electron beam pumped rare gas excimer lamp as VUV-light source. (United States)

    Mühlberger, F; Saraji-Bozorgzad, M; Gonin, M; Fuhrer, K; Zimmermann, R


    Orthogonal acceleration time-of-flight mass spectrometers (oaTOFMS), which are exhibiting a pulsed orthogonal extraction of ion bunches into the TOF mass analyzer from a continuous primary ion beam, are well-suited for continuous ionization methods such as electron impact ionization (EI). Recently an electron beam pumped rare gas excimer lamp (EBEL) was introduced, which emits intensive vacuum UV (VUV) radiation at, e.g., 126 nm (argon excimer) and is well suited as the light source for soft single photon ionization (SPI) of organic molecules. In this paper, a new compact oaTOFMS system which allows switching between SPI, using VUV-light from an EBEL-light source, and conventional EI is described. With the oaTOFMS system, EBEL-SPI and EI mass spectral transients can be recorded at very high repetition rates (up to 100 kHz), enabling high duty cycles and therefore good detection efficiencies. By using a transient recorder card with the capability to perform on-board accumulation of the oaTOF transients, final mass spectra with a dynamic range of 106 can be saved to the hard disk at a rate of 10 Hz. As it is possible to change the ionization modes (EI and SPI) rapidly, a comprehensive monitoring of complex gases with highly dynamic compositions, such as cigarette smoke, is possible. In this context, the EI based mass spectra address the bulk composition (compounds such as water, oxygen, carbon dioxide, etc. in the up to percentage concentration range) as well as some inorganic trace gases such as argon, sulfur dioxide, etc. down to the low ppm level. The EBEL-SPI mass spectra on the other hand are revealing the organic composition down to the lower ppb concentration range.

  12. Dynamic detection of spin accumulation in ferromagnet-semiconductor devices by ferromagnetic resonance (Conference Presentation) (United States)

    Crowell, Paul A.; Liu, Changjiang; Patel, Sahil; Peterson, Tim; Geppert, Chad C.; Christie, Kevin; Stecklein, Gordon; Palmstrøm, Chris J.


    A distinguishing feature of spin accumulation in ferromagnet-semiconductor devices is its precession in a magnetic field. This is the basis for detection techniques such as the Hanle effect, but these approaches become ineffective as the spin lifetime in the semiconductor decreases. For this reason, no electrical Hanle measurement has been demonstrated in GaAs at room temperature. We show here that by forcing the magnetization in the ferromagnet to precess at resonance instead of relying only on the Larmor precession of the spin accumulation in the semiconductor, an electrically generated spin accumulation can be detected up to 300 K. The injection bias and temperature dependence of the measured spin signal agree with those obtained using traditional methods. We further show that this new approach enables a measurement of short spin lifetimes (techniques. The measurements were carried out on epitaxial Heusler alloy (Co2FeSi or Co2MnSi)/n-GaAs heterostructures. Lateral spin valve devices were fabricated by electron beam and photolithography. We compare measurements carried out by the new FMR-based technique with traditional non-local and three-terminal Hanle measurements. A full model appropriate for the measurements will be introduced, and a broader discussion in the context of spin pumping experimenments will be included in the talk. The new technique provides a simple and powerful means for detecting spin accumulation at high temperatures. Reference: C. Liu, S. J. Patel, T. A. Peterson, C. C. Geppert, K. D. Christie, C. J. Palmstrøm, and P. A. Crowell, "Dynamic detection of electron spin accumulation in ferromagnet-semiconductor devices by ferromagnetic resonance," Nature Communications 7, 10296 (2016).

  13. Handbook of spintronic semiconductors

    CERN Document Server

    Chen, Weimin


    Offers a review of the field of spintronic semiconductors. This book covers a range of topics, including growth and basic physical properties of diluted magnetic semiconductors based on II-VI, III-V and IV semiconductors, developments in theory and experimental techniques and potential device applications.

  14. DNA detection by THz pumping

    Energy Technology Data Exchange (ETDEWEB)

    Chernev, A. L. [Russian Academy of Sciences, St. Petersburg Academic University—Nanotechnology Research and Education Centre (Russian Federation); Bagraev, N. T.; Klyachkin, L. E. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Emelyanov, A. K.; Dubina, M. V. [Russian Academy of Sciences, St. Petersburg Academic University—Nanotechnology Research and Education Centre (Russian Federation)


    DNA semiconductor detection and sequencing is considered to be the most promising approach for future discoveries in genome and proteome research which is dramatically dependent on the challenges faced by semiconductor nanotechnologies. DNA pH-sensing with ion-sensitive field effect transistor (ISFET) is well-known to be a successfully applied electronic platform for genetic research. However this method lacks fundamentally in chemical specificity. Here we develop the first ever silicon nanosandwich pump device, which provides both the excitation of DNA fragments’ self-resonant modes and the feedback for current-voltage measurements at room temperature. This device allows direct detection of singlestranded label-free oligonucleotides by measuring their THz frequency response in aqueous solution. These results provide a new insight into the nanobioelectronics for the future real-time technologies of direct gene observations.

  15. Development of the power control system for semiconductor lasers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kwang Suk; Kim, Cheol Jung


    For the first year plan of this program, we developed the power control system for semiconductor lasers. We applied the high-current switching mode techniques to fabricating a power control system. Then, we investigated the direct side pumping techniques with GaA1As diode laser bars to laser crystal without pumping optics. We obtained 0.5W average output power from this DPSSL. (author). 54 refs., 3 tabs., 18 figs.

  16. An Electron-Beam Controlled Semiconductor Switch (United States)


    of the Seventeenth Power Modulator Symposium, Seattle, WA, pp. 214-218. 1986. 21. Bovino , L., ’ioumans,R., Weiner, H., Burke, T . , "Optica lly... Bovino , R. Youmans, M. Weiner, and T. Burke, ’ ’Optically Co ntrolled Semiconducto r Switch for ~lulti-~legawatt Rep-Rated Pulse r s ," Conf. Record...p. 615. (II 1 W. N. Carr, IEEE Trans. Electron Devices, vol. ED-12, p. 531 , 1965. (121 T. Burke, M. Weiner. L. Bovino , and R. Youmans, in Proc

  17. Electron beam recrystallization of amorphous semiconductor materials (United States)

    Evans, J. C., Jr.


    Nucleation and growth of crystalline films of silicon, germanium, and cadmium sulfide on substrates of plastic and glass were investigated. Amorphous films of germanium, silicon, and cadmium sulfide on amorphous substrates of glass and plastic were converted to the crystalline condition by electron bombardment.

  18. A compact differential laser Doppler velocimeter using a semiconductor laser

    NARCIS (Netherlands)

    Jentink, H.W.; Beurden, van J.A.J.; Helsdingen, M.A.; Mul, de F.F.M.; Suichies, H.E.; Aarnoudse, J.G.; Greve, J.


    A small differential laser Doppler velocimeter which uses a semiconductor laser and a small number of optical components is described. In this device the light from the laser diode is split into coherent beams by means of a diffraction grating. The two first-order beams are crossed in a probe volume

  19. Pumps; Pumpen

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, H. [Gesellschaft fuer Praktische Energiekunde e.V., Muenchen (Germany). Forschungsstelle fuer Energiewirtschaft; Hellriegel, E. [Gesellschaft fuer Praktische Energiekunde e.V., Muenchen (Germany). Forschungsstelle fuer Energiewirtschaft; Pfitzner, G. [Gesellschaft fuer Praktische Energiekunde e.V., Muenchen (Germany). Forschungsstelle fuer Energiewirtschaft


    The technical features of commercial pump types are described with regard to their technical, energy-related and economic parameters, and characteristic data are presented in the form of data sheets. This is to provide a basis for a comparative assessment of different technologies and technical variants. The chapter `System specifications` describes the various fields of application of pumps and the resulting specific requirements. The design and function of the different pump types are described in `Technical description`. `System and plant description dscribes the design and adaptation of pumps, i.e. the adaptation of the plant data to the system requirements. `Data compilation` provides a survey of the types and systematics of the compiled data as well as a decision aid for selecting the pumps best suited to the various applications. The `Data sheet` section describes the structure and handling of the data sheets as well as the data contained therein. The data sheets are contained in the apapendix of this report. The section `General analysis` compares typical technical, energy-related and economic characteristics of the different pump types. This is to enable a rough comparison of pump types and to facilitate decisions. The chapter `Example` illustrates the use of the data sheets by means of a selected example. (orig./GL) [Deutsch] Die vorliegende Arbeit hat zum Ziel, Technik seriengefertigter und marktgaengiger Pumpen in typisierter Form hinsichtlich ihrer technischen, energetischen und wirtschaftlichen Parameter zu beschreiben und ihre charakteristischen Kennwerte in Datenblaettern abzubilden. Damit wird ein grundlegendes Instrument fuer die vergleichende Beurteilung unterschiedlicher Techniken bzw. Technikvarianten hinsichtlich energetischer und wirtschaftlicher Kriterien geschaffen. Im Abschnitt `Systemanforderungen` erfolgt die Beschreibung der einzelnen Anwendungsbereiche fuer Pumpen mit den speziellen daraus resultierenden Anforderungen. Der Aufbau und

  20. Organo luminescent semiconductor nanocrystal probes for biological applications and process for making and using such probes (United States)

    Weiss, Shimon; Bruchez, Jr., Marcel; Alivisatos, Paul


    A semiconductor nanocrystal compound is described capable of linking to an affinity molecule. The compound comprises (1) a semiconductor nanocrystal capable of emitting electromagnetic radiation and/or absorbing energy, and/or scattering or diffracting electromagnetic radiation--when excited by an electromagnetic radiation source or a particle beam; and (2) an affinity molecule linked to the semiconductor nanocrystal. The semiconductor nanocrystal is linked to an affinity molecule to form a semiconductor nanocrystal probe capable of bonding with a detectable substance. Exposure of the semiconductor nanocrystal to excitation energy will excite the semiconductor nanocrystal causing the emission of electromagnetic radiation. Further described are processes for respectively: making the luminescent semiconductor nanocrystal compound; making the semiconductor nanocrystal probe; and using the probe to determine the presence of a detectable substance in a material.


    Institute of Scientific and Technical Information of China (English)

    邢明明; 董世民; 崔阳; 陈培毅


    A beam pumping system is of the following characteristics:1) the rotating speed of the motor changes instantaneously; 2) the load torque of a belt-driving unit fluctuates greatly; 3) the longitudinal elastic deformation of the belt changes instantaneously.With the belt simplified as two springs of no mass,and with the motor speed fluctuation,the sliding friction between the belt and the pulleys as well as the influences of the belt transmission's instantaneous load torque on the pulley sliding angle and equivalent spring stiffness taken into consideration,a dynamic simulation model of a belt driving unit of a beam pumping system is built.According to the simulation results of the driving-driven pulley's momentary speed and the instantaneous output torque of the motor,the simulation model of belt instantaneous transmission efficiency of beam pumping units is established.Simulation results show that:1) the motor rotating speed fluctuates periodically,and the higher frequency fluctuation of the motor rotating speed is made by the belt's alternating longitudinal elastic deformation; 2) there is a rotating variation loss between the driving-pulley and the driven-pulley,and the belt transmission efficiency is reduced by the driven-pulley speed loss; 3) after the system achieves a stable running state,the transmission efficiency of the belt unit changes periodically,and its varying amplitude depends on fluctuating characteristics of the load torque.Average transmission efficiency is decreasing with the load torque increasing,and it is also decreasing with the torque balance degree decreasing; 4) belt's average transmission efficiency of a beam pumping unit is usually less than 90%.When the load torque is bigger and the torque balance degree is smaller,it is possible that the average transmission efficiency of the belt driving unit is less than 85%.%针对游梁式抽油机电动机转速存在波动、皮带传动负载扭矩波动大、皮带纵向弹性变形交变

  2. Light-Matter Interaction and Lasing in Semiconductor Nanowires: A combined FDTD and Semiconductor Bloch Equation Approach

    CERN Document Server

    Buschlinger, Robert; Peschel, Ulf


    We present a time-domain model for the simulation of light-matter interaction in semiconductors in arbitrary geometries and across a wide range of excitation conditions. The electromagnetic field is treated classically using the finite-difference time-domain method. The polarization and occupation numbers of the semiconductor material are described using the semiconductor Bloch equations including many-body effects in the screened Hartree-Fock approximation. Spontaneous emission noise is introduced using stochastic driving terms. As an application of the model, we present simulations of the dynamics of a nanowire laser including optical pumping, seeding by spontaneous emission and the selection of lasing modes.

  3. Forschungszentrum Rossendorf, Institute of Ion Beam Physics and Materials Research. Annual report 2004

    Energy Technology Data Exchange (ETDEWEB)

    Borany, J. von; Heera, V.; Helm, M.; Jaeger, H.U.; Moeller, W. (eds.)


    The following topics are dealt with: Silicon based electrically driven microcavity LED, ultraviolet electroluminescence from a Gd-implanted Si-metal-oxide-semiconductor device, semiconductor quantum-cascade lasers, ion beam synthesis and morphology of semiconductor memories, ion implantation, films, sputtering, ion-beam induced destabilization of nanoparticles. (HSI)


    DEFF Research Database (Denmark)


    The present invention relates to a compact, reliable and low-cost coherent LIDAR (Light Detection And Ranging) system for remote wind-speed determination, determination of particle concentration, and/or temperature based on an all semiconductor light source and related methods. The present...... invention provides a coherent LIDAR system comprising a semiconductor laser for emission of a measurement beam of electromagnetic radiation directed towards a measurement volume for illumination of particles in the measurement volume, a reference beam generator for generation of a reference beam, a detector...

  5. Types of Breast Pumps (United States)

    ... Devices Consumer Products Breast Pumps Types of Breast Pumps Share Tweet Linkedin Pin it More sharing options ... used for feeding a baby. Types of Breast Pumps There are three basic types of breast pumps: ...

  6. Unitary lens semiconductor device (United States)

    Lear, Kevin L.


    A unitary lens semiconductor device and method. The unitary lens semiconductor device is provided with at least one semiconductor layer having a composition varying in the growth direction for unitarily forming one or more lenses in the semiconductor layer. Unitary lens semiconductor devices may be formed as light-processing devices such as microlenses, and as light-active devices such as light-emitting diodes, photodetectors, resonant-cavity light-emitting diodes, vertical-cavity surface-emitting lasers, and resonant cavity photodetectors.

  7. A novel electro-optical pump-probe system for bioelectromagnetic investigations (United States)

    De Angelis, Annalisa; Couderc, Vincent; Leproux, Philippe; Labruyère, Alexis; Tonello, Alessandro; El Amari, Saad; Arnaud-Cormos, Delia; Leveque, Philippe


    In the area of bioelectromagnetic studies there is a growing interest to understand the mechanisms leading to nanosecond electric fields induced electroporation. Real-time imaging techniques at molecular level could probably bring further advances on how electric fields interact with living cells. However the investigations are limited by the present-day lack of these kinds of advanced instrumentations. In this context, we present an innovative electro-optical pump-probe system. The aim of our project is to provide a performing and compact device for electrical stimulation and multiplex Coherent anti-Stokes Raman Scattering (M-CARS) imaging of biological cells at once. The system consists of a 1064 nm sub-nanosecond laser source providing both a monochromatic pump and a polychromatic Stokes optical beam used in a CARS process, as well as the trigger beam for the optoelectronic switching-based electrical pulse generator. The polychromatic Stokes beam (from 600 to 1700 nm) results from a supercontinuum generation in a photonic crystal fiber (PCF). A detailed spectro-temporal characterization of such a broadband spectrum shows the impact of the nonlinear propagation in the fiber on the Stokes wave. Despite the temporal distortions observable on Stokes pulse profiles, their spectral synchronization with the pump pulse remains possible and efficient in the interesting region between 1100 nm and 1700 nm. The electrical stimulation device consists of a customized generator combining microstrip-line technology and laser-triggered photoconductive semiconductor switches. Our experimental characterization highlights the capability for such a generator to control the main pulse parameters (profile, amplitude and duration) and to be easily synchronized with the imaging system. We finally test and calibrate the system by means of a KDP crystal. The preliminary results suggest that this electro-optical system provides a suitable tool for real-time investigation of

  8. Packaging and Performance of 980nm Broad Area Semiconductor Lasers

    Institute of Scientific and Technical Information of China (English)


    High power broad area semiconductor lasers have found increasing applications in pumping of solid state laser systems and fiber amplifiers, frequency doubling, medical systems and material processing.Packaging including the assembly design, process and thermal management, has a significant impact on the optical performance and reliability of a high power broad area laser. In this paper, we introduce the package structures and assembling process of 980nm broad area lasers and report the performances including output power, thermal behavior and far fields.We will report two types of high power broad area laser assemblies.One is a microchannel liquid cooled assembly and the other is a conduction cooled CT-mount assembly. Optical powers of 15W and 10W were achieved from a 980nm broad area laser with a 120 μ m stripe width in a microchannel liquid cooled assembly and conduction cooled CT-mount assembly, respectively.Furthermore,a high power of 6.5W out of fiber was demonstrated from a pigtailed, fully packaged butterfly-type module without TEC (Thermoelectric cooler).The measurement results showed that thermal management is the key in not only improving output power, but also significantly improving beam divergence and far field distribution.The results also showed that the die attach solder can significant impact the reliability of high power broad area lasers and that indium solder is not suitable for high power laser applications due to electromigration at high current densities and high temperatures.

  9. Ultrafast terahertz emission properties in GaAs semiconductor (United States)

    Wang, Aihua; Shi, Yulei; Zhou, Qingli


    Ultrafast carrier dynamics in Schottky barriers is an extremely active area of research in recent years. The observation of the generation of terahertz pulses from metal/semiconductor interfaces provides a technique to characterize electronic properties of these materials. However, a detailed analysis of these phenomena has not been performed satisfactorily. In this work, the measurements of optically generated terahertz emission from Au/GaAs interfaces are investigated in detail. We observe that, under high laser power excitation, terahertz signals from bare GaAs wafers and Au/GaAs samples exhibit an opposite polarity. The polarity-flip behaviors in the terahertz beams are also observed in the temperature-dependent measurements and the femtosecond pump-generation studies of the Au/GaAs interfaces. These effects can be fully explained in terms of the dynamics of carrier transfer in the Au/GaAs Schottky barriers, which involves the internal photoelectric emission and the electron tunneling effect, and picosecond time constants are found for these processes.

  10. Nuclear-Pumped Lasers. [efficient conversion of energy liberated in nuclear reactions to coherent radiation (United States)


    The state of the art in nuclear pumped lasers is reviewed. Nuclear pumped laser modeling, nuclear volume and foil excitation of laser plasmas, proton beam simulations, nuclear flashlamp excitation, and reactor laser systems studies are covered.

  11. Semiconductor quantum dot amplifiers for optical signal processing

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Uskov, A. V.; Bischoff, Svend


    The dynamics of quantum dot semiconductor amplifiers are investigated theoretically with respect to the potential for ultrafast signal processing. The high-speed signal processing capacity of these devices is found to be limited by the wetting layer dynamics in case of electrical pumping, while...

  12. Semiconductor quantum dot amplifiers for optical signal processing

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Uskov, A. V.; Bischoff, Svend


    The dynamics of quantum dot semiconductor amplifiers are investigated theoretically with respect to the potential for ultrafast signal processing. The high-speed signal processing capacity of these devices is found to be limited by the wetting layer dynamics in case of electrical pumping, while...

  13. Semimetal/Semiconductor Nanocomposites for Thermoelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Hong [Univ. of California, Santa Barbara, CA (United States). Materials Dept.; Burke, Peter G. [Univ. of California, Santa Barbara, CA (United States). Materials Dept.; Gossard, Arthur C. [Univ. of California, Santa Barbara, CA (United States). Materials Dept.; Zeng, Gehong [Univ. of California, Santa Barbara, CA (United States). Dept. of Electrical and Computer Engineering; Ramu, Ashok T. [Univ. of California, Santa Barbara, CA (United States). Dept. of Electrical and Computer Engineering; Bahk, Je-Hyeong [Univ. of California, Santa Barbara, CA (United States). Dept. of Electrical and Computer Engineering; Bowers, John E. [Univ. of California, Santa Barbara, CA (United States). Dept. of Electrical and Computer Engineering


    In this work, we present research on semimetal-semiconductor nanocomposites grown by molecular beam epitaxy (MBE) for thermoelectric applications. We study several different III-V semiconductors embedded with semimetallic rare earth-group V (RE-V) compounds, but focus is given here to ErSb:InxGa1-xSb as a promising p-type thermoelectric material. Nano­structures of RE-V compounds are formed and embedded within the III-V semiconductor matrix. By codoping the nanocomposites with the appropriate dopants, both n-type and p-type materials have been made for thermoelectric applications. The thermoelectric properties have been engineered for enhanced thermoelectric device performance. Segmented thermoelectric power generator modules using 50 μm thick Er-containing nanocomposites have been fabricated and measured. Research on different rare earth elements for thermoelectrics is discussed.

  14. Semiconductor Physical Electronics

    CERN Document Server

    Li, Sheng


    Semiconductor Physical Electronics, Second Edition, provides comprehensive coverage of fundamental semiconductor physics that is essential to an understanding of the physical and operational principles of a wide variety of semiconductor electronic and optoelectronic devices. This text presents a unified and balanced treatment of the physics, characterization, and applications of semiconductor materials and devices for physicists and material scientists who need further exposure to semiconductor and photonic devices, and for device engineers who need additional background on the underlying physical principles. This updated and revised second edition reflects advances in semicondutor technologies over the past decade, including many new semiconductor devices that have emerged and entered into the marketplace. It is suitable for graduate students in electrical engineering, materials science, physics, and chemical engineering, and as a general reference for processing and device engineers working in the semicondi...

  15. Properties of Optical Resonant Modes in Ⅲ-Nitride Semiconductor Micro-Cone Cavities

    Institute of Scientific and Technical Information of China (English)

    DAI Lun; ZHANG Bei; LIN Jing-Yu; JIANG Hong-Xing


    Arrays of Ⅲ-nitride semiconductor micro-cone cavities with a base diameter of 3.3μm were fabricated by ion beam etching. The micro-cones consisted of 58 nm thick multiple quantum wells of ln0.22Ga0.78N/In0.06Ga0.94N as well as a 1.5μm thick epilayer of GaN. Optical resonant modes from a single micro-cone could be clearly observed in the photoluminescence spectra at temperatures up to 200K under a pumping power density two orders of magnitude lower than that for the Ⅲ-nitride semiconductor micro-disk or micro-ring cavity. Using a novel optical ray tracing method, we have figured out four main types of optical resonant cavities inside the three-dimensional micro-cone, including two Fabry-Perot (F-P) mode types as well as two Whispering Gallery mode types. The three corresponding mode spacings among the four agree perfectly with the experimental results. The advantages of this new class of micro-cavity over the other micro-cavities are discussed. These findings are expected to have an impact on the design of the ultraviolet/blue micro-cavity laser diodes.

  16. Frequency dependence of the pump-to-signal RIN transfer in fiber optical parametric amplifiers

    DEFF Research Database (Denmark)

    Pakarzadeh Dezfuli Nezhad, Hassan; Rottwitt, Karsten; Zakery, A.


    Using a numerical model, the frequency dependence of the pump-to-signal RIN transfer in FOPAs has been investigated. The model includes fiber loss, pump depletion as well as difference in group velocity among interacting beams.......Using a numerical model, the frequency dependence of the pump-to-signal RIN transfer in FOPAs has been investigated. The model includes fiber loss, pump depletion as well as difference in group velocity among interacting beams....

  17. Wave optics simulation of diode pumped alkali laser (DPAL) (United States)

    Endo, Masamori; Nagaoka, Ryuji; Nagaoka, Hiroki; Nagai, Toru; Wani, Fumio


    A numerical simulation code for a diode pumped alkali laser (DPAL) was developed. The code employs the Fresnel- Kirchhoff diffraction integral for both laser mode and pump light propagations. A three-dimensional rate equation set was developed to determine the local gain. The spectral divergence of the pump beam was represented by a series of monochromatic beams with different wavelengths. The calculated results showed an excellent agreements with relevant experimental results. It was found that the main channel of the pump power drain is the spontaneous emission from the upper level of the lasing transition.

  18. Single photon ionization time-of-flight mass spectrometry with a pulsed electron beam pumped excimer VUV lamp for on-line gas analysis: setup and first results on cigarette smoke and human breath. (United States)

    Mühlberger, F; Streibel, T; Wieser, J; Ulrich, A; Zimmermann, R


    Single-photon ionization (SPI) using vacuum ultraviolet (VUV) light produced by an electron beam pumped rare gas excimer source has been coupled to a compact and mobile time-of-flight mass spectrometer (TOFMS). The novel device enables real-time on-line monitoring of organic trace substances in complex gaseous matrixes down to the ppb range. The pulsed VUV radiation of the light source is employed for SPI in the ion source of the TOFMS. Ion extraction is also carried out in a pulsed mode with a short time delay with respect to ionization. The experimental setup of the interface VUV light source/time-of-flight mass spectrometer is described, and the novel SPI-TOFMS system is characterized by means of standard calibration gases. Limits of detection down to 50 ppb for aliphatic and aromatic hydrocarbons were achieved. First on-line applications comprised real-time measurements of aromatic and aliphatic trace compounds in mainstream cigarette smoke, which represents a highly dynamic fluctuating gaseous matrix. Time resolution was sufficient to monitor the smoking process on a puff-by-puff resolved basis. Furthermore, human breath analysis has been carried out to detect differences in the breath of a smoker and a nonsmoker, respectively. Several well-known biomarkers for smoke could be identified in the smoker's breath. The possibility for even shorter measurement times while maintaining the achieved sensitivity makes this new device a promising tool for on-line analysis of organic trace compounds in process gases or biological systems.

  19. Semiconductor Electrical Measurements Laboratory (United States)

    Federal Laboratory Consortium — The Semiconductor Electrical Measurements Laboratory is a research laboratory which complements the Optical Measurements Laboratory. The laboratory provides for Hall...

  20. Semiconductor bridge (SCB) detonator (United States)

    Bickes, Jr., Robert W.; Grubelich, Mark C.


    The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge igniter that comprises a pair of electrically conductive lands connected by a semiconductor bridge. The semiconductor bridge is in operational or direct contact with the explosive material, whereby current flowing through the semiconductor bridge causes initiation of the explosive material. Header wires connected to the electrically-conductive lands and electrical feed-throughs of the header posts of explosive devices, are substantially coaxial to the direction of current flow through the SCB, i.e., substantially coaxial to the SCB length.

  1. Dewatering gas wells with pneumatic pumping equipment

    Energy Technology Data Exchange (ETDEWEB)

    Nickell, R.L.


    El Paso Natural Gas Co. has been operating pumping units on gas wells since 1964. At present, the company operates some 69 pumping units in the E. Panhandle field in Texas and the S. Erick field in Oklahoma. Of these 6 are pneumatic units and the remainder is conventional beam type units powered by gas-fueled engines or electric motors. A graphical representation of the data obtained from the El Paso wells in which various lift facilities are installed is included. These data show initial cost, maintenance cost, and lift cost per barrel of (1) gas engine beam unit; (2) electric beam unit; (3) pneumatic unit; (4) gas lift; and (5) intermitter. While not a panacea for all dewatering ills, pneumatic pumping represents an economical tool which may be applied to a wide range of conditions.

  2. Radio pumping of ionospheric plasma with orbital angular momentum. (United States)

    Leyser, T B; Norin, L; McCarrick, M; Pedersen, T R; Gustavsson, B


    Experimental results are presented of pumping ionospheric plasma with a radio wave carrying orbital angular momentum (OAM), using the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. Optical emissions from the pumped plasma turbulence exhibit the characteristic ring-shaped morphology when the pump beam carries OAM. Features of stimulated electromagnetic emissions (SEE) that are attributed to cascading Langmuir turbulence are well developed for a regular beam but are significantly weaker for a ring-shaped OAM beam in which case upper hybrid turbulence dominates the SEE.

  3. Semiconductor Laser Tracking Frequency Distance Gauge (United States)

    Phillips, James D.; Reasenberg, Robert D.


    Advanced astronomical missions with greatly enhanced resolution and physics missions of unprecedented accuracy will require a spaceworthy laser distance gauge of substantially improved performance. The Tracking Frequency Gauge (TFG) uses a single beam, locking a laser to the measurement interferometer. We have demonstrated this technique with pm (10(exp -12) m) performance. We report on the version we are now developing based on space-qualifiable, fiber-coupled distributed-feedback semiconductor lasers.

  4. Plasma/Neutral-Beam Etching Apparatus (United States)

    Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert


    Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

  5. Plasma/Neutral-Beam Etching Apparatus (United States)

    Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert


    Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

  6. Pump characteristics and applications

    CERN Document Server

    Volk, Michael


    Providing a wealth of information on pumps and pump systems, Pump Characteristics and Applications, Third Edition details how pump equipment is selected, sized, operated, maintained, and repaired. The book identifies the key components of pumps and pump accessories, introduces the basics of pump and system hydraulics as well as more advanced hydraulic topics, and details various pump types, as well as special materials on seals, motors, variable frequency drives, and other pump-related subjects. It uses example problems throughout the text, reinforcing the practical application of the formulae

  7. Moving Space Charge Field Effects in Photoconductive Semiconductors and Their Applications. (United States)

    Wang, Chen-Chia


    Internal electric space charge fields are formed inside photoconductive semiconductors when they are illuminated by an optical interference pattern. This Thesis focuses on the effects of such space charge fields formed inside semiconductor materials which contain both donors and deep level traps for photo-excited charge carriers. The photon energies are less than the band gap of the photoconductive semiconductor. The space charge field arises from the migration of photo-excited charges from the brighter to darker regions of the optical interference pattern where they become trapped. If the center frequencies of the two mutually coherent optical fields which form the interference pattern are unequal, the interference pattern and consequently the internal space charge field move with identical velocity. The moving space charge field results in a net photocurrent output from the material even when no external electric bias field is present. The short-circuit photocurrents contain a wealth of information about the material characteristics of the photoconductive semiconductor which, once known, can be used to deduce information about the optical frequency spectrum of the optical fields which form the interference pattern. An approximate but very accurate mathematical characterization of the short-circuit photocurrents and their properties are presented. These properties were verified by direct experimental measurements performed in the photoconductive semiconductors InP:Fe, GaAs, GaAs:Cr, CdTe:V, and CdTe:V:Mn. If the two interfering optical fields are plane waves with negligible linewidth, a DC short-circuit photocurrent results whose properties can be used to determine the sign of the pre-dominant species of photo-excited charge carriers, their mobility-lifetime products, and some information about donor and trap concentrations if the mobilities are known. All experiments were performed with laser diode pumped Nd:YAG unidirectional ring oscillator lasers whose optical

  8. Extracting hot carriers from photoexcited semiconductor nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaoyang


    This research program addresses a fundamental question related to the use of nanomaterials in solar energy -- namely, whether semiconductor nanocrystals (NCs) can help surpass the efficiency limits, the so-called “Shockley-Queisser” limit, in conventional solar cells. In these cells, absorption of photons with energies above the semiconductor bandgap generates “hot” charge carriers that quickly “cool” to the band edges before they can be utilized to do work; this sets the solar cell efficiency at a limit of ~31%. If instead, all of the energy of the hot carriers could be captured, solar-to-electric power conversion efficiencies could be increased, theoretically, to as high as 66%. A potential route to capture this energy is to utilize semiconductor nanocrystals. In these materials, the quasi-continuous conduction and valence bands of the bulk semiconductor become discretized due to confinement of the charge carriers. Consequently, the energy spacing between the electronic levels can be much larger than the highest phonon frequency of the lattice, creating a “phonon bottleneck” wherein hot-carrier relaxation is possible via slower multiphonon emission. For example, hot-electron lifetimes as long as ~1 ns have been observed in NCs grown by molecular beam epitaxy. In colloidal NCs, long lifetimes have been demonstrated through careful design of the nanocrystal interfaces. Due to their ability to slow electronic relaxation, semiconductor NCs can in principle enable extraction of hot carriers before they cool to the band edges, leading to more efficient solar cells.


    DEFF Research Database (Denmark)


    invention provides a coherent LIDAR system comprising a semiconductor laser for emission of a measurement beam of electromagnetic radiation directed towards a measurement volume for illumination of particles in the measurement volume, a reference beam generator for generation of a reference beam, a detector......The present invention relates to a compact, reliable and low-cost coherent LIDAR (Light Detection And Ranging) system for remote wind-speed determination, determination of particle concentration, and/or temperature based on an all semiconductor light source and related methods. The present...... for generation of a detector signal by mixing of the reference beam with light emitted from the particles in the measurement volume illuminated by the measurement beam, and a signal processor for generating a velocity signal corresponding to the velocity of the particles based on the detector signal....

  10. Semiconductors data handbook

    CERN Document Server

    Madelung, Otfried


    This volume Semiconductors: Data Handbook contains frequently used data from the corresponding larger Landolt-Börnstein handbooks in a low price book for the individual scientist working in the laboratory. The Handbook contain important information about a large number of semiconductors

  11. Semiconductor Research Experimental Techniques

    CERN Document Server

    Balkan, Naci


    The book describes the fundamentals, latest developments and use of key experimental techniques for semiconductor research. It explains the application potential of various analytical methods and discusses the opportunities to apply particular analytical techniques to study novel semiconductor compounds, such as dilute nitride alloys. The emphasis is on the technique rather than on the particular system studied.

  12. Semiconductor radiation detection systems

    CERN Document Server


    Covers research in semiconductor detector and integrated circuit design in the context of medical imaging using ionizing radiation. This book explores other applications of semiconductor radiation detection systems in security applications such as luggage scanning, dirty bomb detection and border control.

  13. Compound Semiconductor Radiation Detectors

    CERN Document Server

    Owens, Alan


    Although elemental semiconductors such as silicon and germanium are standard for energy dispersive spectroscopy in the laboratory, their use for an increasing range of applications is becoming marginalized by their physical limitations, namely the need for ancillary cooling, their modest stopping powers, and radiation intolerance. Compound semiconductors, on the other hand, encompass such a wide range of physical and electronic properties that they have become viable competitors in a number of applications. Compound Semiconductor Radiation Detectors is a consolidated source of information on all aspects of the use of compound semiconductors for radiation detection and measurement. Serious Competitors to Germanium and Silicon Radiation Detectors Wide-gap compound semiconductors offer the ability to operate in a range of hostile thermal and radiation environments while still maintaining sub-keV spectral resolution at X-ray wavelengths. Narrow-gap materials offer the potential of exceeding the spectral resolutio...

  14. Laser systems configured to output a spectrally-consolidated laser beam and related methods (United States)

    Koplow, Jeffrey P [San Ramon, CA


    A laser apparatus includes a plurality of pumps each of which is configured to emit a corresponding pump laser beam having a unique peak wavelength. The laser apparatus includes a spectral beam combiner configured to combine the corresponding pump laser beams into a substantially spatially-coherent pump laser beam having a pump spectrum that includes the unique peak wavelengths, and first and second selectively reflective elements spaced from each other to define a lasing cavity including a lasing medium therein. The lasing medium generates a plurality of gain spectra responsive to absorbing the pump laser beam. Each gain spectrum corresponds to a respective one of the unique peak wavelengths of the substantially spatially-coherent pump laser beam and partially overlaps with all other ones of the gain spectra. The reflective elements are configured to promote emission of a laser beam from the lasing medium with a peak wavelength common to each gain spectrum.

  15. Bidirectional beam propagation method (United States)

    Kaczmarski, P.; Lagasse, P. E.


    A bidirectional extension of the beam propagation method (BPM) to optical waveguides with a longitudinal discontinuity is presented. The algorithm is verified by computing a reflection of the TE(0) mode from a semiconductor laser facet. The bidirectional BPM is applicable to other configurations such as totally reflecting waveguide mirrors, an abruption transition in a waveguide, or a waveguide with many discontinuities generating multiple reflections. The method can also be adapted to TM polarization.

  16. A new polarimeter scheme based on solid state semiconductors Un nuevo esquema para polarímetros basado en semiconductor de estado sólido


    Heiner Castro Gutierrez


    A new kind of polarimeter scheme is suggested using solid state semiconductors. The new approach is based on the modulation over the intensities of the diffracted beams through a two-dimensional chiral grating, reported recently. It will be demonstrated that at least four intensity measurements of no equivalent diffracted beams are needed in order to estimate the polarization state of the incident beam. The incident beam azimuth was varied by routing a linear polarizer lens mounting in a step...

  17. LMFBR with booster pump in pumping loop (United States)

    Rubinstein, H.J.


    A loop coolant circulation system is described for a liquid metal fast breeder reactor (LMFBR) utilizing a low head, high specific speed booster pump in the hot leg of the coolant loop with the main pump located in the cold leg of the loop, thereby providing the advantages of operating the main pump in the hot leg with the reliability of cold leg pump operation.

  18. Heat pump technology

    CERN Document Server

    Von Cube, Hans Ludwig; Goodall, E G A


    Heat Pump Technology discusses the history, underlying concepts, usage, and advancements in the use of heat pumps. The book covers topics such as the applications and types of heat pumps; thermodynamic principles involved in heat pumps such as internal energy, enthalpy, and exergy; and natural heat sources and energy storage. Also discussed are topics such as the importance of the heat pump in the energy industry; heat pump designs and systems; the development of heat pumps over time; and examples of practical everyday uses of heat pumps. The text is recommended for those who would like to kno

  19. Reduced filamentation in high power semiconductor lasers

    DEFF Research Database (Denmark)

    Skovgaard, Peter M. W.; McInerney, John; O'Brien, Peter


    High brightness semiconductor lasers have applications in fields ranging from material processing to medicine. The main difficulty associated with high brightness is that high optical power densities cause damage to the laser facet and thus require large apertures. This, in turn, results in spatio...... in the optical field causes spatial hole-burning and thus filamentation. To reduce filamentation we propose a new, relatively simple design based on inhomogeneous pumping in which the injected current has a gradual transverse profile. We confirm the improved laser performance theoretically and experimentally...

  20. Optically pumped mid-infrared light emitter on silicon (United States)

    Elizondo, L. A.; Li, Y.; Sow, A.; Kamana, R.; Wu, H. Z.; Mukherjee, S.; Zhao, F.; Shi, Z.; McCann, P. J.


    Characterization of a IV-VI semiconductor structure consisting of a PbSe/PbSrSe multiple quantum well (MQW) active region between distributed Bragg reflectors grown by molecular beam epitaxy on a Si(111) substrate is described. Pulsed photoluminescence (PL) spectra exhibited interband electronic transition energies ranging linearly with temperature from 231.4 meV at 150 K to 299.4 meV at 300 K, while continuous wave (cw) PL spectra exhibited only the vertical optical cavity mode with emission varying between 299.2 meV at 150 K to 301.1 meV at 300 K. A maximum PL emission power of approximately 1.8 mW was obtained for cw diode laser pumping when the heat sink temperature was 200 K. Data are consistent with a localized epilayer heating effect of about 100 deg where the interband electronic transition energy is coincident with the vertical optical cavity mode. In spite of significant sample heating and associated thermal expansion mismatch stress, cw PL emission intensity was stable with no noticeable degradation in intensity after repeated measurements. These results show that IV-VI epitaxial layers on silicon are viable materials for fabricating reliable light emitters for on-chip optical interconnects.

  1. A plateau in the sensitivity of a compact optically pumped atomic magnetometer

    Directory of Open Access Journals (Sweden)

    Natsuhiko Mizutani


    Full Text Available In a compact optically pumped atomic magnetometer (OPAM, there is a plateau in the sensitivity where the dependence of the sensitivity on pumping power is small compared with that predicted by the uniform polarization model. The mechanism that generates this plateau was explained by numerical analysis. The distribution of spin polarization in the alkali metal cell of an OPAM was modeled using the Bloch equation incorporating a diffusion term and an equation for the attenuation of the pump beam. The model was well-fitted to the experimental results for a module with a cubic cell with 20 mm sides and pump and probe beams with 8 mm diameter. On the plateau, strong magnetic response was generated at the regions that were not illuminated directly by the intense pump beam, while at the same time spin polarization as large as 0.5 was maintained due to diffusion of the spin-polarized atoms. Thus, the sensitivity of the magnetometer monitored with a probe beam decreases only slightly with increasing pump beam intensity because the spin polarization under an intense pump beam is saturated. This plateau, which is characteristic of this type of magnetometer using a narrow pump and probe beams, can be used in arrays of magnetometers because it enables stable operation with little sensitivity fluctuation from changes in pump beam power.

  2. A Novel All-optical Wavelength Converter Based on Self-pump Four-wave Mixing

    Institute of Scientific and Technical Information of China (English)

    CHEN Jianxiao; CHEN Zhangyuan; TAO Zhenning; WU Deming; XU Anshi; WANG Ziyu


    A novel scheme of all-optical wavelength converter(AOWC) based on dual pump four-wave mixing(DP-FWM) was demonstrated. To suppress the ASE noise of the semiconductor optical amplifier (SOA), one of the two pumps was generated interiorly from a loop laser constructed mainly by tunable optical filter and SOA. The theoretical model and some experimental results were presented.

  3. Transverse Mode Formation in Longitudinally Pumped Miniature Slab Lasers

    Institute of Scientific and Technical Information of China (English)

    XU Jian-Qiu; YE Xin; FANG Tao


    The formation of transverse modes in longitudinally pumped miniature slab lasers is investigated theoretically and experimentally. The longitudinally non-uniform gain-guiding is studied by expanding the electric field into the Hermite-Gaussian functions that satisfy boundary conditions of the resonator. Non-Gaussian transversal beam profiles in the near field are found and the beam diameter is reduced when the pump spot becomes smaller. The experimental observation agrees with the theoretical calculation.

  4. 600-W lamp pumped CW Nd:YAG laser

    Institute of Scientific and Technical Information of China (English)

    Qiang Li(李强); Zhimin Wang(王志敏); Zhiyong Wang(王智勇); Zhensheng Yu(于振声); Hong Lei(雷訇); Jiang Guo(郭江); Gang Li(李港); Tiechuan Zuo(左铁钏)


    A lamp pumped CW Nd:YAG laser is presented in this paper for the requirement of industrial application.The main factors, which affect output power and beam quality of high power solid-state laser module, are theoretically analyzed. Total electro-optics efficiency of lamp pumped Nd:YAG crystal as high as 4.0% is obtained, and output power is higher than 647 W with beam parameter product 22 mm.mrad.

  5. Coherent dynamics in semiconductors

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher


    Ultrafast nonlinear optical spectroscopy is used to study the coherent dynamics of optically excited electron-hole pairs in semiconductors. Coulomb interaction implies that the optical inter-band transitions are dominated, at least at low temperatures, by excitonic effects. They are further...... and molecular systems are found and studied in the exciton-biexciton system of semiconductors. At densities where strong exciton interactions, or many-body effects, become dominant, the semiconductor Bloch equations present a more rigorous treatment of the phenomena Ultrafast degenerate four-wave mixing is used...

  6. Defects in semiconductors

    CERN Document Server

    Romano, Lucia; Jagadish, Chennupati


    This volume, number 91 in the Semiconductor and Semimetals series, focuses on defects in semiconductors. Defects in semiconductors help to explain several phenomena, from diffusion to getter, and to draw theories on materials' behavior in response to electrical or mechanical fields. The volume includes chapters focusing specifically on electron and proton irradiation of silicon, point defects in zinc oxide and gallium nitride, ion implantation defects and shallow junctions in silicon and germanium, and much more. It will help support students and scientists in their experimental and theoret

  7. Physics of semiconductor lasers

    CERN Document Server

    Mroziewicz, B; Nakwaski, W


    Written for readers who have some background in solid state physics but do not necessarily possess any knowledge of semiconductor lasers, this book provides a comprehensive and concise account of fundamental semiconductor laser physics, technology and properties. The principles of operation of these lasers are therefore discussed in detail with the interrelations between their design and optical, electrical and thermal properties. The relative merits of a large number of laser structures and their parameters are described to acquaint the reader with the various aspects of the semiconductor l

  8. Slow Light Semiconductor Laser (United States)


    we demonstrate a semiconductor laser with a spectral linewidth of 18 kHz in the telecom band around 1:55um. The views, opinions and/or findings...we demonstrate a semiconductor laser with a spectral linewidth of 18 kHz in the telecom band around 1:55um. Further, the large intracavity field...hybrid Si/III- V platforms Abstract The semiconductor laser is the principal light source powering the world-wide optical fiber network . Ever

  9. Semiconductors bonds and bands

    CERN Document Server

    Ferry, David K


    As we settle into this second decade of the twenty-first century, it is evident that the advances in micro-electronics have truly revolutionized our day-to-day lifestyle. The technology is built upon semiconductors, materials in which the band gap has been engineered for special values suitable to the particular application. This book, written specifically for a one semester course for graduate students, provides a thorough understanding of the key solid state physics of semiconductors. It describes how quantum mechanics gives semiconductors unique properties that enabled the micro-electronics revolution, and sustain the ever-growing importance of this revolution.

  10. Vanadium-pumped titanium x-ray laser

    Energy Technology Data Exchange (ETDEWEB)

    Nilsen, J.


    A resonantly photo-pumped x-ray laser is formed of a vanadium and titanium foil combination that is driven by two beams of intense line focused optical laser radiation. Ground state neon-like titanium ions are resonantly photo-pumped by line emission from fluorine-like vanadium ions.

  11. Spectral Feature Analysis of Semiconductor Thin Disk Laser

    Institute of Scientific and Technical Information of China (English)

    HE Chun-feng; QIN Li; LI Jun; CHENG Li-wen; LIANG Xue-mei; NING Yong-qiang; WANG Li-jun


    The semiconductor thin disk laser is a new type of semiconductor laser. This work gives the basic operation function of the semiconductor disk laser, and analyses the heat effect by the experimentally measured photoluminescence spectrum of the laser chip at different pump power and different temperatures. We can see that: with increasing pump power, the thermal effect of the gain material becomes seriously and causes the saturation of carrier lifetime, so the electron-hole pair created in the absorbtion layer has no enough time to rate to one of the wells, and the non-radiative recombination happens in the barrier. When the thermal effect becomes stronger, the chip will be not lasing. This phenomenon is from the smaller energy offset between barrier and quantum well. We optimize the original structure design and experimental technology. A non-absorbing AlGaAs layer which is transparent to the pumping and laser wavelength is added to confine the carriers in the quantum wells. At the same time a DBR with double reflecting band is induced to improve the absorbing efficiency of the pumping light. The single QW is replaced by the three narrow QWs. This three QWs structure can add the quantum state of QW, increase the recombination probability of carriers in the QWs and reduce the heat effect. The chemical etching equipment is also improved to control the surface unevenness to be within 50 nm.

  12. EDITORIAL: Oxide semiconductors (United States)

    Kawasaki, M.; Makino, T.


    Blue or ultraviolet semiconducting light-emitting diodes have the potential to revolutionize illumination systems in the near-future. Such industrial need has propelled the investigation of several wide-gap semiconducting materials in recent years. Commercial applications include blue lasers for DVD memory and laser printers, while military applications are also expected. Most of the material development has so far been focused on GaN (band gap 3.5 eV at 2 K), and ZnSe (2.9 eV) because these two representative direct transition semiconductors are known to be bright emitting sources. GaN and GaN-based alloys are emerging as the winners in this field because ZnSe is subject to defect formation under high current drive. On the other hand, another II-VI compound, ZnO, has also excited substantial interest in the optoelectronics-oriented research communities because it is the brightest emitter of all, owing to the fact that its excitons have a 60 meV binding energy. This is compared with 26 meV for GaN and 20 meV for ZnSe. The stable excitons could lead to laser action based on their recombination even at temperatures well above room temperature. ZnO has additional major properties that are more advantageous than other wide-gap materials: availability of large area substrates, higher energy radiation stability, environmentally-friendly ingredients, and amenability to wet chemical etching. However, ZnO is not new to the semiconductor field as exemplified by several studies made during the 1960s on structural, vibrational, optical and electrical properties (Mollwo E 1982 Landolt-Boernstein New Series vol 17 (Berlin: Springer) p 35). In terms of devices, the luminescence from light-emitting diode structures was demonstrated in which Cu2O was used as the p-type material (Drapak I T 1968 Semiconductors 2 624). The main obstacle to the development of ZnO has been the lack of reproducible p-type ZnO. The possibility of achieving epitaxial p-type layers with the aid of thermal

  13. Induced focusing and conversion of a Gaussian beam into an elliptic Gaussian beam

    Indian Academy of Sciences (India)

    Manoj Mishra; Swapan Konar


    We have presented an investigation of the induced focusing in Kerr media of two laser beams, the pump beam and the probe beam, which could be either Gaussian or elliptic Gaussian or a combination of the two. We have used variational formalism to derive relevant beam-width equations. Among several important findings, the finding that a very week probe beam can be guided and focused when power of both beams are well below their individual threshold for self-focusing, is a noteworthy one. It has been found that induced focusing is not possible for laser beams of any wavelength and beam radius. In case both beams are elliptic Gaussian, we have shown that when power of both beams is above a certain threshold value then the effective radius of both beams collapses and collapse distance depends on power. Moreover, it has been found that induced focusing can be employed to convert a circular Gaussian beam into an elliptic Gaussian beam.

  14. Singly-resonant sum frequency generation of visible light in a semiconductor disk laser

    DEFF Research Database (Denmark)

    Andersen, Martin Thalbitzer; Schlosser, P.J.; Hastie, J.E.;


    In this paper a generic approach for visible light generation is presented. It is based on sum frequency generation between a semiconductor disk laser and a solid-state laser, where the frequency mixing is achieved within the cavity of the semiconductor disk laser using a singlepass of the solid-...... spectrum, by appropriate choice of semiconductor material and single-pass laser wavelength.......In this paper a generic approach for visible light generation is presented. It is based on sum frequency generation between a semiconductor disk laser and a solid-state laser, where the frequency mixing is achieved within the cavity of the semiconductor disk laser using a singlepass of the solid......-state laser light. This exploits the good beam quality and high intra-cavity power present in the semiconductor disk laser to achieve high conversion efficiency. Combining sum frequency mixing and semiconductor disk lasers in this manner allows in principle for generation of any wavelength within the visible...

  15. 80 nm tunable DBR-free semiconductor disk laser (United States)

    Yang, Z.; Albrecht, A. R.; Cederberg, J. G.; Sheik-Bahae, M.


    We report a widely tunable optically pumped distributed Bragg reflector (DBR)-free semiconductor disk laser with 6 W continuous wave output power near 1055 nm when using a 2% output coupler. Using only high reflecting mirrors, the lasing wavelength is centered at 1034 nm and can be tuned up to a record 80 nm by using a birefringent filter. We attribute such wide tunability to the unique broad effective gain bandwidth of DBR-free semiconductor disk lasers achieved by eliminating the active mirror geometry.

  16. Physics of semiconductor devices

    CERN Document Server

    Rudan, Massimo


    This book describes the basic physics of semiconductors, including the hierarchy of transport models, and connects the theory with the functioning of actual semiconductor devices.  Details are worked out carefully and derived from the basic physics, while keeping the internal coherence of the concepts and explaining various levels of approximation. Examples are based on silicon due to its industrial importance. Several chapters are included that provide the reader with the quantum-mechanical concepts necessary for understanding the transport properties of crystals. The behavior of crystals incorporating a position-dependent impurity distribution is described, and the different hierarchical transport models for semiconductor devices are derived (from the Boltzmann transport equation to the hydrodynamic and drift-diffusion models). The transport models are then applied to a detailed description of the main semiconductor-device architectures (bipolar, MOS). The final chapters are devoted to the description of s...

  17. Biggest semiconductor installed

    CERN Multimedia


    Scientists and technicians at the European Laboratory for Particle Physics, commonly known by its French acronym CERN (Centre Europen pour la Recherche Nuclaire), have completed the installation of the largest semiconductor silicon detector.

  18. Defects in semiconductor nanostructures

    Indian Academy of Sciences (India)

    Vijay A Singh; Manoj K Harbola; Praveen Pathak


    Impurities play a pivotal role in semiconductors. One part in a million of phosphorous in silicon alters the conductivity of the latter by several orders of magnitude. Indeed, the information age is possible only because of the unique role of shallow impurities in semiconductors. Although work in semiconductor nanostructures (SN) has been in progress for the past two decades, the role of impurities in them has been only sketchily studied. We outline theoretical approaches to the electronic structure of shallow impurities in SN and discuss their limitations. We find that shallow levels undergo a SHADES (SHAllow-DEep-Shallow) transition as the SN size is decreased. This occurs because of the combined effect of quantum confinement and reduced dielectric constant in SN. Level splitting is pronounced and this can perhaps be probed by ESR and ENDOR techniques. Finally, we suggest that a perusal of literature on (semiconductor) cluster calculations carried out 30 years ago would be useful.

  19. Isotopically controlled semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Haller, E.E.


    A review of recent research involving isotopically controlled semiconductors is presented. Studies with isotopically enriched semiconductor structures experienced a dramatic expansion at the end of the Cold War when significant quantities of enriched isotopes of elements forming semiconductors became available for worldwide collaborations. Isotopes of an element differ in nuclear mass, may have different nuclear spins and undergo different nuclear reactions. Among the latter, the capture of thermal neutrons which can lead to neutron transmutation doping, can be considered the most important one for semiconductors. Experimental and theoretical research exploiting the differences in all the properties has been conducted and will be illustrated with selected examples. Manuel Cardona, the longtime editor-in-chief of Solid State Communications has been and continues to be one of the major contributors to this field of solid state physics and it is a great pleasure to dedicate this review to him.

  20. A semiconductor laser

    Energy Technology Data Exchange (ETDEWEB)

    Naoko, O.; Masaru, K.


    A semiconductor laser with enhanced characteristics is patented in which bleaching coatings are generated on the outcoupling mirrors by sputtering alternating coating layers made from A1203 and A10, with high and low indices of refraction.

  1. Centrifugal pump handbook

    CERN Document Server

    Pumps, Sulzer


    This long-awaited new edition is the complete reference for engineers and designers working on pump design and development or using centrifugal pumps in the field. This authoritative guide has been developed with access to the technical expertise of the leading centrifugal pump developer, Sulzer Pumps. In addition to providing the most comprehensive centrifugal pump theory and design reference with detailed material on cavitation, erosion, selection of materials, rotor vibration behavior and forces acting on pumps, the handbook also covers key pumping applications topics and operational

  2. Radiation effects in semiconductors

    CERN Document Server


    There is a need to understand and combat potential radiation damage problems in semiconductor devices and circuits. Written by international experts, this book explains the effects of radiation on semiconductor devices, radiation detectors, and electronic devices and components. These contributors explore emerging applications, detector technologies, circuit design techniques, new materials, and innovative system approaches. The text focuses on how the technology is being used rather than the mathematical foundations behind it. It covers CMOS radiation-tolerant circuit implementations, CMOS pr


    This state-of-the-art survey on silicon carbide for semiconductors includes a bibliography of the most important references published as of the end...of 1964. The various methods used for growing silicon carbide single crystals are reviewed, as well as their properties and devices fabricated from...them. The fact that the state of-the-art of silicon carbide semiconductors is not further advanced may be attributed to the difficulties of growing

  4. Plasmonic pumping of excitonic photoluminescence in hybrid MoS2-Au nanostructures. (United States)

    Najmaei, Sina; Mlayah, Adnen; Arbouet, Arnaud; Girard, Christian; Léotin, Jean; Lou, Jun


    We report on the fabrication of monolayer MoS2-coated gold nanoantennas combining chemical vapor deposition, e-beam lithography surface patterning, and a soft lift-off/transfer technique. The optical properties of these hybrid plasmonic-excitonic nanostructures are investigated using spatially resolved photoluminescence spectroscopy. Off- and in-resonance plasmonic pumping of the MoS2 excitonic luminescence showed distinct behaviors. For plasmonically mediated pumping, we found a significant enhancement (∼65%) of the photoluminescence intensity, clear evidence that the optical properties of the MoS2 monolayer are strongly influenced by the nanoantenna surface plasmons. In addition, a systematic photoluminescence broadening and red-shift in nanoantenna locations is observed which is interpreted in terms of plasmonic enhanced optical absorption and subsequent heating of the MoS2 monolayers. Using a temperature calibration procedure based on photoluminescence spectral characteristics, we were able to estimate the local temperature changes. We found that the plasmonically induced MoS2 temperature increase is nearly four times larger than in the MoS2 reference temperatures. This study shines light on the plasmonic-excitonic interaction in these hybrid metal/semiconductor nanostructures and provides a unique approach for the engineering of optoelectronic devices based on the light-to-current conversion.

  5. Nuclear pumped laser research at the Jet Propulsion Laboratory (United States)

    Russell, G. R.


    Using a partially nuclear excited xenon flashlamp to pump an iodine laser, laser pulse shapes were analyzed with and without nuclear flashlamp augmentation. The pulse shapes indicate that the deposition of nuclear energy is equally as effective as electrical energy deposition in producing laser pulse energy output. The amplification of the E-beam pumped CF3I was measured at pressures of several atmospheres. Preliminary data shows that, for a part of the iodine laser pulse, amplification of almost a factor of two is measured. This measurement indicates that the gain in an E-beam pumped CF3I is an order of magnitude greater than in the coaxial laser tube.

  6. Longitudinal analysis of semiconductor lasers with low reflectivity facets

    Energy Technology Data Exchange (ETDEWEB)

    Baets, R.; Lagasse, P.E.; Vande Capelle, J.P.


    An analysis is made of longitudinal effects in semiconductor lasers with low facet reflectivities. For this purpose, a self-consistent model is used based on the beam propagation method, which takes into account both the lateral and longitudinal dimension. The calculations show that longitudinal effects have a significant influence on the output fields in the laser.

  7. Static gain saturation in quantum dot semiconductor optical amplifiers. (United States)

    Meuer, Christian; Kim, Jungho; Laemmlin, Matthias; Liebich, Sven; Capua, Amir; Eisenstein, Gadi; Kovsh, Alexey R; Mikhrin, Sergey S; Krestnikov, Igor L; Bimberg, Dieter


    Measurements of saturated amplified spontaneous emission-spectra of quantum dot semiconductor optical amplifiers demonstrate efficient replenishment of the quantum-dot ground state population from excited states. This saturation behavior is perfectly modeled by a rate equation model. We examined experimentally the dependence of saturation on the drive current and the saturating optical pump power as well as on the pump wavelength. A coherent noise spectral hole is observed with which we assess dynamical properties and propose optimization of the SOA operating parameters for high speed applications.

  8. Single ion implantation in semiconductor nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Niepelt, Raphael; Johannes, Andreas; Gnauck, Martin; Slowik, Irma; Geburt, Sebastian; Ronning, Carsten [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet, Jena (Germany)


    Ion implantation is well established as a standard doping technique for semiconductor nanowires. The concentration of dopant atoms per area is typically determined by total beam current monitoring during the irradiation. However, at extremely low ion fluencies, it is not possible to distinguish the exact number of implanted ions in a nanometer sized structure, as the ions are distributed statistically over the irradiated area that is usually far wider than the nanostructure of interest. In our experiments we implanted electrically contacted semiconductor nanostructures that were connected to a preamplifier/amplifier setup. As with every impinging ion a certain amount of energy is deposited inside the material, one can detect signals directly induced by the ion implantation and the nanostructures themselves can act as a radiation sensor. This leads to a countable and very precisely adjustable ion dose during the implantation down to doping with single ions.

  9. Epitaxy of Semiconductors Introduction to Physical Principles

    CERN Document Server

    Pohl, Udo W


    Introduction to Epitaxy provides the essential information for a comprehensive upper-level graduate course treating the crystalline growth of semiconductor heterostructures. Heteroepitaxy represents the basis of advanced electronic and optoelectronic devices today and is considered one of the top fields in materials research. The book covers the structural and electronic properties of strained epitaxial layers, the thermodynamics and kinetics of layer growth, and the description of the major growth techniques metalorganic vapor phase epitaxy, molecular beam epitaxy and liquid phase epitaxy. Cubic semiconductors, strain relaxation by misfit dislocations, strain and confinement effects on electronic states, surface structures and processes during nucleation and growth are treated in detail. The Introduction to Epitaxy requires only little knowledge on solid-state physics. Students of natural sciences, materials science and electrical engineering as well as their lecturers benefit from elementary introductions t...

  10. Lattice Location of Transition Metals in Semiconductors

    CERN Multimedia


    %IS366 %title\\\\ \\\\Transition metals (TMs) in semiconductors have been the subject of considerable research for nearly 40 years. This is due both to their role as important model impurities for deep centers in semiconductors, and to their technological impact as widespread contaminants in Si processing, where the miniaturization of devices requires to keep their sheet concentration below 10$^{10}$ cm$^{-2}$. As a consequence of the low TM solubility, conventional ion beam methods for direct lattice location have failed completely in identifying the lattice sites of isolated transition metals. Although electron paramagnetic resonance (EPR) has yielded valuable information on a variety of TM centers, it has been unable to detect certain defects considered by theory, e.g., isolated interstitial or substitutional Cu in Si. The proposed identity of other EPR centers such as substitutional Fe in Si, still needs confirmation by additional experimental methods. As a consequence, the knowledge on the structural propert...

  11. Imaging the motion of electrons across semiconductor heterojunctions (United States)

    Man, Michael K. L.; Margiolakis, Athanasios; Deckoff-Jones, Skylar; Harada, Takaaki; Wong, E. Laine; Krishna, M. Bala Murali; Madéo, Julien; Winchester, Andrew; Lei, Sidong; Vajtai, Robert; Ajayan, Pulickel M.; Dani, Keshav M.


    Technological progress since the late twentieth century has centred on semiconductor devices, such as transistors, diodes and solar cells. At the heart of these devices is the internal motion of electrons through semiconductor materials due to applied electric fields or by the excitation of photocarriers. Imaging the motion of these electrons would provide unprecedented insight into this important phenomenon, but requires high spatial and temporal resolution. Current studies of electron dynamics in semiconductors are generally limited by the spatial resolution of optical probes, or by the temporal resolution of electronic probes. Here, by combining femtosecond pump-probe techniques with spectroscopic photoemission electron microscopy, we imaged the motion of photoexcited electrons from high-energy to low-energy states in a type-II 2D InSe/GaAs heterostructure. At the instant of photoexcitation, energy-resolved photoelectron images revealed a highly non-equilibrium distribution of photocarriers in space and energy. Thereafter, in response to the out-of-equilibrium photocarriers, we observed the spatial redistribution of charges, thus forming internal electric fields, bending the semiconductor bands, and finally impeding further charge transfer. By assembling images taken at different time-delays, we produced a movie lasting a few trillionths of a second of the electron-transfer process in the photoexcited type-II heterostructure—a fundamental phenomenon in semiconductor devices such as solar cells. Quantitative analysis and theoretical modelling of spatial variations in the movie provide insight into future solar cells, 2D materials and other semiconductor devices.

  12. Intracavity interferometry using synchronously pumped OPO (United States)

    Zavadilová, Alena; Vyhlídal, David; Kubeček, Václav; Šulc, Jan; Navrátil, Petr


    The concept of system for intracavity interferometry based on the beat note detection in subharmonic synchronously intracavity pumped optical parametrical oscillator (OPO) is presented. The system consisted of SESAM-modelocked, picosecond, diode pumped Nd:YVO4 laser, operating at wavelength 1.06 μm and tunable linear intracavity pumped OPO based on MgO:PPLN crystal, widely tunable in 1.5 μm able to deliver two independent trains of picosecond pulses. The optical length of the OPO cavity was set to be exactly twice the pumping cavity length. In this configuration the OPO produces signal pulses with the same repetition frequency as the pump laser but the signal consists of two completely independent pulse trains. For purpose of pump probe measurements the setup signal with half repetition rate and scalable amplitude was derived from the OPO signal using RF signal divider, electropotical modulator and fiber amplifier. The impact of one pump beam on the sample is detected by one probing OPO train, the other OPO train is used as a reference. The beat note measured using the intracavity interferometer is proportional to phase modulation caused by the pump beam. The bandwidth of observed beat-note was less than 1 Hz (FWHM), it corresponds to a phase shift measurement error of less than 1.5 × 10-7 rad without any active stabilization. Such compact low-cost system could be used for ultra-sensitive phase-difference measurements (e.g. nonlinear refractive index measurement) for wide range of material especially in spectral range important for telecom applications.

  13. Airy beams from a microchip laser

    CERN Document Server

    Longhi, Stefano


    It is theoretically shown that an end-pumped microchip laser formed by a thin laser crystal with plane-plane but slightly tilted facets can emit, under appropriate pumping conditions and near a crystal edge, a truncated self-accelerating Airy output beam.

  14. Alternative backing up pump for turbomolecular pumps (United States)

    Myneni, Ganapati Rao


    As an alternative to the use of a mechanical backing pump in the application of wide range turbomolecular pumps in ultra-high and extra high vacuum applications, palladium oxide is used to convert hydrogen present in the evacuation stream and related volumes to water with the water then being cryo-pumped to a low pressure of below about 1.e.sup.-3 Torr at K. Cryo-pumping is achieved using a low cost Kleemenco cycle cryocooler, a somewhat more expensive thermoelectric cooler, a Venturi cooler or a similar device to achieve the required minimization of hydrogen partial pressure.

  15. Coherent laser beam combining

    CERN Document Server

    Brignon, Arnaud


    Recently, the improvement of diode pumping in solid state lasers and the development of double clad fiber lasers have allowed to maintain excellent laser beam quality with single mode fibers. However, the fiber output power if often limited below a power damage threshold. Coherent laser beam combining (CLBC) brings a solution to these limitations by identifying the most efficient architectures and allowing for excellent spectral and spatial quality. This knowledge will become critical for the design of the next generation high-power lasers and is of major interest to many industrial, environme

  16. Novel sucker rod pumping system based on linear motor technology

    Institute of Scientific and Technical Information of China (English)

    李立毅; 李立清; 吴红星; 胡余生; 邹积岩


    Obtaining petroleum at the cost of electrical energy is a common problem in almost all oil fields, and it is mainly caused by low duty radio of induction motor used in beam pumping units. Traditional beam-pumping units have many intrinsic disadvantages such as low efficiency, complex transmission devices, poor flexibility,tremendous volume and weight in long stroke, etc. Therefore, a novel direct driven linear electromagnetic pumping unit (EMPU) has been developed by combining oil extraction technology with linear motor technology. The thrust of EMPU matches the changing of suspension center load to improve the system efficiency and cut down the consumption of energy. Based on previous experience, a small-scale prototype was developed and a simulation was conducted with it. Both theoretical analyses and experimental study showed that the problems exiting in beam pumping units can be solved with EMPU system, and this is a new method which can be used to solve high energy waste in oil fields.

  17. Method of doping a semiconductor (United States)

    Yang, Chiang Y.; Rapp, Robert A.


    A method for doping semiconductor material. An interface is established between a solid electrolyte and a semiconductor to be doped. The electrolyte is chosen to be an ionic conductor of the selected impurity and the semiconductor material and electrolyte are jointly chosen so that any compound formed from the impurity and the semiconductor will have a free energy no lower than the electrolyte. A potential is then established across the interface so as to allow the impurity ions to diffuse into the semiconductor. In one embodiment the semiconductor and electrolyte may be heated so as to increase the diffusion coefficient.

  18. Development of high current electron beam generator

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byeong Cheol; Lee, Jong Min; Kim, Sun Kook [and others


    A high-current electron beam generator has been developed. The energy and the average current of the electron beam are 2 MeV and 50 mA, respectively. The electron beam generator is composed of an electron gun, RF acceleration cavities, a 260-kW RF generator, electron beam optics components, and control system, etc. The electron beam generator will be used for the development of a millimeter-wave free-electron laser and a high average power infrared free-electron laser. The machine will also be used as a user facility in nuclear industry, environment industry, semiconductor industry, chemical industry, etc. (author). 15 tabs., 85 figs.

  19. Transmission of electrons inside the cryogenic pumps of ITER injector

    Energy Technology Data Exchange (ETDEWEB)

    Veltri, P., E-mail:; Sartori, E. [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova (Italy)


    Large cryogenic pumps are installed in the vessel of large neutral beam injectors (NBIs) used to heat the plasma in nuclear fusion experiments. The operation of such pumps can be compromised by the presence of stray secondary electrons that are generated along the beam path. In this paper, we present a numerical model to analyze the propagation of the electrons inside the pump. The aim of the study is to quantify the power load on the active pump elements, via evaluation of the transmission probabilities across the domain of the pump. These are obtained starting from large datasets of particle trajectories, obtained by numerical means. The transmission probability of the electrons across the domain is calculated for the NBI of the ITER and for its prototype Megavolt ITer Injector and Concept Advancement (MITICA) and the results are discussed.

  20. Transmission of electrons inside the cryogenic pumps of ITER injector. (United States)

    Veltri, P; Sartori, E


    Large cryogenic pumps are installed in the vessel of large neutral beam injectors (NBIs) used to heat the plasma in nuclear fusion experiments. The operation of such pumps can be compromised by the presence of stray secondary electrons that are generated along the beam path. In this paper, we present a numerical model to analyze the propagation of the electrons inside the pump. The aim of the study is to quantify the power load on the active pump elements, via evaluation of the transmission probabilities across the domain of the pump. These are obtained starting from large datasets of particle trajectories, obtained by numerical means. The transmission probability of the electrons across the domain is calculated for the NBI of the ITER and for its prototype Megavolt ITer Injector and Concept Advancement (MITICA) and the results are discussed.

  1. Large electromagnetic pumps. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Kilman, G.B.


    The development of large electromagnetic pumps for the liquid metal heat transfer systems of fission reactors has progressed for a number of years. Such pumps are now planned for fusion reactors and solar plants as well. The Einstein-Szilard (annular) pump has been selected as the preferred configuration. Some of the reasons that electromagnetic pumps may be preferred over mechanical pumps and why the annular configuration was selected are discussed. A detailed electromagnetic analysis of the annular pump, based on slug flow, is presented. The analysis is then used to explore the implications of large size and power on considerations of electromagnetic skin effect, geometric skin effect and the cylindrical geometry.

  2. Self-Pulsating Semiconductor Lasers Theory and Experiment

    CERN Document Server

    Mirasso, C R; Hernández-García, E; Lenstra, D; Lynch, S; Landais, P; Phelan, P; O'Gorman, J; San Miguel, M; Elsasser, W


    We report detailed measurements of the pump-current dependency of the self-pulsating frequency of semiconductor CD lasers. A distinct kink in this dependence is found and explained using rate-equation model. The kink denotes a transition between a region where the self-pulsations are weakly sustained relaxation oscillations and a region where Q-switching takes place. Simulations show that spontaneous emission noise plays a crucial role for the cross-over.

  3. Beyond amorphous organic semiconductors (United States)

    Hanna, Jun-ichi


    Recently it has been discovered that some types of liquid crystals, which believed to be governed by ionic conduction, exhibit a very fast electronic conduction. Their charge carrier transport is characterized by high mobility over 10-2 cm2/Vs independent of electric field and temperature. Now, the liquid crystals are being recognized as a new class of organic semiconductors. In this article, a new aspect of liquid crystals as a self-organizing molecular semiconductor are reviewed, focused on their basic charge carrier transport properties and discussed in comparison with those of molecular crystals and amorphous materials. And it is concluded that the liquid crystal is promising as a quality organic semiconductor for the devices that require a high mobility.

  4. Photoelectronic properties of semiconductors

    CERN Document Server

    Bube, Richard H


    The interaction between light and electrons in semiconductors forms the basis for many interesting and practically significant properties. This book examines the fundamental physics underlying this rich complexity of photoelectronic properties of semiconductors, and will familiarise the reader with the relatively simple models that are useful in describing these fundamentals. The basic physics is also illustrated with typical recent examples of experimental data and observations. Following introductory material on the basic concepts, the book moves on to consider a wide range of phenomena, including photoconductivity, recombination effects, photoelectronic methods of defect analysis, photoeffects at grain boundaries, amorphous semiconductors, photovoltaic effects and photoeffects in quantum wells and superlattices. The author is Professor of Materials Science and Electrical Engineering at Stanford University, and has taught this material for many years. He is an experienced author, his earlier books having fo...

  5. Semiconductors for organic transistors

    Directory of Open Access Journals (Sweden)

    Antonio Facchetti


    Full Text Available Organic molecules/polymers with a π-conjugated (heteroaromatic backbone are capable of transporting charge and interact efficiently with light. Therefore, these systems can act as semiconductors in opto-electronic devices similar to inorganic materials. However, organic chemistry offers tools for tailoring materials' functional properties via modifications of the molecular/monomeric units, opening new possibilities for inexpensive device manufacturing. This article reviews the fundamental aspects behind the structural design/realization of p- (hole transporting and n-channel (electron-transporting semiconductors for organic field-effect transistors (OFETs. An introduction to OFET principles and history, as well as of the state-of-the-art organic semiconductor structure and performance of OFETs is provided.

  6. Fundamentals of semiconductor lasers

    CERN Document Server

    Numai, Takahiro


    This book explains physics under the operating principles of semiconductor lasers in detail based on the experience of the author, dealing with the first manufacturing of phase-shifted DFB-LDs and recent research on transverse modes.   The book also bridges a wide gap between journal papers and textbooks, requiring only an undergraduate-level knowledge of electromagnetism and quantum mechanics, and helps readers to understand journal papers where definitions of some technical terms vary, depending on the paper. Two definitions of the photon density in the rate equations and two definitions of the phase-shift in the phase-shifted DFB-LD are explained, and differences in the calculated results are indicated, depending on the definitions.    Readers can understand the physics of semiconductor lasers and analytical tools for Fabry-Perot LDs, DFB-LDs, and VCSELs and will be stimulated to develop semiconductor lasers themselves.

  7. Basic Semiconductor Physics

    CERN Document Server

    Hamaguchi, Chihiro


    This book presents a detailed description of the basic semiconductor physics. The reader is assumed to have a basic command of mathematics and some elementary knowledge of solid state physics. The text covers a wide range of important phenomena in semiconductors, from the simple to the advanced. The reader can understand three different methods of energy band calculations, empirical pseudo-potential, k.p perturbation and tight-binding methods. The effective mass approximation and electron motion in a periodic potential, Boltzmann transport equation and deformation potentials used for full band Monte Carlo simulation are discussed. Experiments and theoretical analysis of cyclotron resonance are discussed in detail because the results are essential to the understanding of semiconductor physics. Optical and transport properties, magneto-transport, two dimensional electron gas transport (HEMT and MOSFET), and quantum transport are reviewed, explaining optical transition, electron phonon interactions, electron mob...

  8. Hydrogen in semiconductors II

    CERN Document Server

    Nickel, Norbert H; Weber, Eicke R; Nickel, Norbert H


    Since its inception in 1966, the series of numbered volumes known as Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. The "Willardson and Beer" Series, as it is widely known, has succeeded in publishing numerous landmark volumes and chapters. Not only did many of these volumes make an impact at the time of their publication, but they continue to be well-cited years after their original release. Recently, Professor Eicke R. Weber of the University of California at Berkeley joined as a co-editor of the series. Professor Weber, a well-known expert in the field of semiconductor materials, will further contribute to continuing the series' tradition of publishing timely, highly relevant, and long-impacting volumes. Some of the recent volumes, such as Hydrogen in Semiconductors, Imperfections in III/V Materials, Epitaxial Microstructures, High-Speed Heterostructure Devices, Oxygen in Silicon, and others promise that this tradition ...

  9. Spin-transport-phenomena in metals, semiconductors, and insulators

    Energy Technology Data Exchange (ETDEWEB)

    Althammer, Matthias Klaus


    Assuming that one could deterministically inject, transport, manipulate, store and detect spin information in solid state devices, the well-established concepts of charge-based electronics could be transferred to the spin realm. This thesis explores the injection, transport, manipulation and storage of spin information in metallic conductors, semiconductors, as well as electrical insulators. On the one hand, we explore the spin-dependent properties of semiconducting zinc oxide thin films deposited via laser-molecular beam epitaxy (laser-MBE). After demonstrating that the zinc oxide films fabricated during this thesis have excellent structural, electrical, and optical properties, we investigate the spin-related properties by optical pump/probe, electrical injection/optical detection, and all electrical spin valve-based experiments. The two key results from these experiments are: (i) Long-lived spin states with spin dephasing times of 10 ns at 10 K related to donor bound excitons can be optically addressed. (ii) The spin dephasing times relevant for electrical transport-based experiments are {<=} 2 ns at 10 K and are correlated with structural quality. On the other hand we focus on two topics of current scientific interest: the comparison of the magnetoresistance to the magnetothermopower of conducting ferromagnets, and the investigation of pure spin currents generated in ferromagnetic insulator/normal metal hybrid structures. We investigate the magnetoresistance and magnetothermopower of gallium manganese arsenide and Heusler thin films as a function of external magnetic field orientation. Using a series expansion of the resistivity and Seebeck tensors and the inherent symmetry of the sample's crystal structure, we show that a full quantitative extraction of the transport tensors from such experiments is possible. Regarding the spin currents in ferromagnetic insulator/normal metal hybrid structures we studied the spin mixing conductance in yttrium iron garnet

  10. Pump element for a tube pump

    DEFF Research Database (Denmark)


    The invention relates to a tube pump comprising a tube and a pump element inserted in the tube, where the pump element comprises a rod element and a first and a second non-return valve member positioned a distance apart on the rod element. The valve members are oriented in the same direction rela...... to a part of the tube. The invention further relates to a method for creating a flow of a fluid within an at least partly flexible tube by means of a pump element as mentioned above.......The invention relates to a tube pump comprising a tube and a pump element inserted in the tube, where the pump element comprises a rod element and a first and a second non-return valve member positioned a distance apart on the rod element. The valve members are oriented in the same direction...... portion acts to alternately close and open the valve members thereby generating a fluid flow through the tube. The invention further relates to a pump element comprising at least two non-return valve members connected by a rod element, and for insertion in an at least partly flexible tube in such tube...

  11. Structure, stability, and spectra of lateral modes of a broad-area semiconductor laser

    DEFF Research Database (Denmark)

    Blaaberg, Søren; Petersen, Paul Michael; Tromborg, Bjarne


    We present a theoretical analysis of the lateral modes of a broad-area semiconductor laser. The structure of the modes are classified into four categories and the modes are traced in the frequency versus pump rate diagram. It is shown how the branches of the frequency tuning curves for the differ......We present a theoretical analysis of the lateral modes of a broad-area semiconductor laser. The structure of the modes are classified into four categories and the modes are traced in the frequency versus pump rate diagram. It is shown how the branches of the frequency tuning curves...

  12. Optical processes in semiconductors

    CERN Document Server

    Pankove, Jacques I


    Based on a series of lectures at Berkeley, 1968-1969, this is the first book to deal comprehensively with all of the phenomena involving light in semiconductors. The author has combined, for the graduate student and researcher, a great variety of source material, journal research, and many years of experimental research, adding new insights published for the first time in this book.Coverage includes energy states in semiconductors and their perturbation by external parameters, absorption, relationships between optical constants, spectroscopy, radiative transitions, nonradiative recombination

  13. Compound semiconductor device physics

    CERN Document Server

    Tiwari, Sandip


    This book provides one of the most rigorous treatments of compound semiconductor device physics yet published. A complete understanding of modern devices requires a working knowledge of low-dimensional physics, the use of statistical methods, and the use of one-, two-, and three-dimensional analytical and numerical analysis techniques. With its systematic and detailed**discussion of these topics, this book is ideal for both the researcher and the student. Although the emphasis of this text is on compound semiconductor devices, many of the principles discussed will also be useful to those inter

  14. Ternary chalcopyrite semiconductors

    CERN Document Server

    Shay, J L; Pamplin, B R


    Ternary Chalcopyrite Semiconductors: Growth, Electronic Properties, and Applications covers the developments of work in the I-III-VI2 and II-IV-V2 ternary chalcopyrite compounds. This book is composed of eight chapters that focus on the crystal growth, characterization, and applications of these compounds to optical communications systems. After briefly dealing with the status of ternary chalcopyrite compounds, this book goes on describing the crystal growth of II-IV-V2 and I-III-VI2 single crystals. Chapters 3 and 4 examine the energy band structure of these semiconductor compounds, illustrat

  15. Advances in semiconductor lasers

    CERN Document Server

    Coleman, James J; Jagadish, Chennupati


    Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. Originally widely known as the ""Willardson and Beer"" Series, it has succeeded in publishing numerous landmark volumes and chapters. The series publishes timely, highly relevant volumes intended for long-term impact and reflecting the truly interdisciplinary nature of the field. The volumes in Semiconductors and Semimetals have been and will continue to be of great interest to physicists, chemists, materials scientists, and device engineers in academia, scien

  16. Semiconductor opto-electronics

    CERN Document Server

    Moss, TS; Ellis, B


    Semiconductor Opto-Electronics focuses on opto-electronics, covering the basic physical phenomena and device behavior that arise from the interaction between electromagnetic radiation and electrons in a solid. The first nine chapters of this book are devoted to theoretical topics, discussing the interaction of electromagnetic waves with solids, dispersion theory and absorption processes, magneto-optical effects, and non-linear phenomena. Theories of photo-effects and photo-detectors are treated in detail, including the theories of radiation generation and the behavior of semiconductor lasers a

  17. Quantum Transport in Semiconductors (United States)


    SRS i 91 4. TITLE AND SUBTITLE Quantum Transport in Semiconductors 5. FUNDING NUMBER söMtos-rizk-ooss 6. AUTHOR(S) D. K. Ferry ©fte ELECTE...OF ABSTRACT UL NSN 7540-01-280-5500 O 1 9 Standard Form 298 (Rev. 2-89) Presented by ANSI Std «9-18 298-102 Final Report Quantum Transport in... Quantum Transport in Semiconductor Devices This final report describes a program of research investigating quantum effects which become important in

  18. Introductory semiconductor device physics

    CERN Document Server

    Parker, Greg


    ATOMS AND BONDINGThe Periodic TableIonic BondingCovalent BondingMetallic bondingvan der Waals BondingStart a DatabaseENERGY BANDS AND EFFECTIVE MASSSemiconductors, Insulators and MetalsSemiconductorsInsulatorsMetalsThe Concept of Effective MassCARRIER CONCENTRATIONS IN SEMICONDUCTORSDonors and AcceptorsFermi-LevelCarrier Concentration EquationsDonors and Acceptors Both PresentCONDUCTION IN SEMICONDUCTORSCarrier DriftCarrier MobilitySaturated Drift VelocityMobility Variation with TemperatureA Derivation of Ohm's LawDrift Current EquationsSemiconductor Band Diagrams with an Electric Field Presen

  19. Single semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Michler, Peter (ed.) [Stuttgart Univ. (Germany). Inst. fuer Halbleiteroptik und Funktionelle Grenzflaechen


    This book reviews recent advances in the exciting and rapidly growing field of semiconductor quantum dots via contributions from some of the most prominent researchers in the scientific community. Special focus is given to optical, quantum optical, and spin properties of single quantum dots due to their potential applications in devices operating with single electron spins and/or single photons. This includes single and coupled quantum dots in external fields, cavity-quantum electrodynamics, and single and entangled photon pair generation. Single Semiconductor Quantum Dots also addresses growth techniques to allow for a positioned nucleation of dots as well as applications of quantum dots in quantum information technologies. (orig.)

  20. Engineering magnetism in semiconductors

    Directory of Open Access Journals (Sweden)

    Tomasz Dietl


    Full Text Available Transition metal doped III-V, II-VI, and group IV compounds offer an unprecedented opportunity to explore ferromagnetism in semiconductors. Because ferromagnetic spin-spin interactions are mediated by holes in the valence band, changing the Fermi level using co-doping, electric fields, or light can directly manipulate the magnetic ordering. Moreover, engineering the Fermi level position by co-doping makes it possible to modify solubility and self-compensation limits, affecting magnetic characteristics in a number of surprising ways. The Fermi energy can even control the aggregation of magnetic ions, providing a new route to self-organization of magnetic nanostructures in a semiconductor host.

  1. Semiconductor surface protection material (United States)

    Packard, R. D. (Inventor)


    A method and a product for protecting semiconductor surfaces is disclosed. The protective coating material is prepared by heating a suitable protective resin with an organic solvent which is solid at room temperature and converting the resulting solution into sheets by a conventional casting operation. Pieces of such sheets of suitable shape and thickness are placed on the semiconductor areas to be coated and heat and vacuum are then applied to melt the sheet and to drive off the solvent and cure the resin. A uniform adherent coating, free of bubbles and other defects, is thus obtained exactly where it is desired.

  2. A semiconductor laser device employing optical feedback

    Energy Technology Data Exchange (ETDEWEB)

    Tosikhiro, F.; Akimoto, S.; Katsuyuki, F.; Kun, I.


    A method is proposed for obtaining stable lasing parameters using a single longitudinal mode with reduced noise. This method involves reflecting a portion of the laser emission from the semiconductor laser back into the active region. An angular reflector with an angle other than a right angle is used. The laser emission which exits this end of the resonator is collimated by a lens into a parallel beam, which, when reflected off the angular reflector, strikes the lens at specific angles, and is focused at two points on this same end. This makes it possible to obtain single longitudinal mode lasing with significant submodal structure attenuation and a total absence of noise.

  3. Proton pump inhibitors (United States)

    Proton pump inhibitors (PPIs) are medicines that work by reducing the amount of stomach acid made by ... Proton pump inhibitors are used to: Relieve symptoms of acid reflux, or gastroesophageal reflux disease (GERD). This ...

  4. Metal semiconductor contacts and devices

    CERN Document Server

    Cohen, Simon S; Einspruch, Norman G


    VLSI Electronics Microstructure Science, Volume 13: Metal-Semiconductor Contacts and Devices presents the physics, technology, and applications of metal-semiconductor barriers in digital integrated circuits. The emphasis is placed on the interplay among the theory, processing, and characterization techniques in the development of practical metal-semiconductor contacts and devices.This volume contains chapters that are devoted to the discussion of the physics of metal-semiconductor interfaces and its basic phenomena; fabrication procedures; and interface characterization techniques, particularl

  5. Handbook of luminescent semiconductor materials

    CERN Document Server

    Bergman, Leah


    Photoluminescence spectroscopy is an important approach for examining the optical interactions in semiconductors and optical devices with the goal of gaining insight into material properties. With contributions from researchers at the forefront of this field, Handbook of Luminescent Semiconductor Materials explores the use of this technique to study semiconductor materials in a variety of applications, including solid-state lighting, solar energy conversion, optical devices, and biological imaging. After introducing basic semiconductor theory and photoluminescence principles, the book focuses

  6. Pump for Saturated Liquids (United States)

    Elliott, D. G.


    Boiling liquids pumped by device based on proven components. Expanding saturated liquid in nozzle and diverting its phases along separate paths in liquid/vapor separator raises pressure of liquid. Liquid cooled in process. Pump makes it unnecessary to pressurize cryogenic liquids in order to pump them. Problems of introducing noncondensable pressurizing gas avoided.

  7. Intense terahertz excitation of semiconductors

    CERN Document Server

    Ganichev, S D


    This work presents the first comprehensive treatment of high-power terahertz applications to semiconductors and low-dimensional semiconductor structures. Terahertz properties of semiconductors are in the centre of scientific activities because of the need of high-speed electronics.

  8. Azimuthal and radial shaping of vortex beams generated in twisted nonlinear photonic crystals. (United States)

    Shemer, Keren; Voloch-Bloch, Noa; Shapira, Asia; Libster, Ana; Juwiler, Irit; Arie, Ady


    We experimentally demonstrate that the orbital angular momentum (OAM) of a second harmonic (SH) beam, generated within twisted nonlinear photonic crystals, depends both on the OAM of the input pump beam and on the quasi-angular momentum of the crystal. In addition, when the pump's radial index is zero, the radial index of the SH beam is equal to that of the nonlinear crystal. Furthermore, by mixing two noncollinear pump beams in this crystal, we generate, in addition to the SH beams, a new "virtual beam" having multiple values of OAM that are determined by the nonlinear process.

  9. Development of Raman-shifted probe laser beam for plasma diagnosis using polaro-interferometer

    Indian Academy of Sciences (India)

    M P Kamath; A P Kulkarni; S Jain; P K Tripathi; A S Joshi; P A Naik; P D Gupta


    Optical diagnostics of laser-produced plasma requires a coherent, polarized probe beam synchronized with the pump beam. The probe beam should have energy above the background emission of plasma. Though the second harmonic probe beam satisfies most of the requirements, the plasma emission is larger at the harmonic frequencies of the pump. Hence, at high intensities we need a probe beam at non-harmonic frequencies. We have set up a Raman frequency shifted probe beam using a pressurized hydrogen cell that is pumped by the second harmonic of the Nd glass laser that operates at only one Stokes line of 673.75 nm.

  10. A High Efficiency Wavelength Conversion Scheme Based on Four Wave Minxing in a Semiconductor Optical Amplifier

    Institute of Scientific and Technical Information of China (English)


    A new approach of all optical wavelength converter based on four wave mixing (FWM) in a semiconductor optical amplifier (SOA) with the conjugate wave reflected by a fiber Bragg grating (FBG) and then amplified by the SOA is reported. By adjusting the pump power, the conversion efficiency could be improved 7~10dB with signal-to-background-noise-ratio (SBR) deteriorated 1~2dB, compared with traditional single pump four wave mixing.

  11. Biexcitons in semiconductor microcavities

    DEFF Research Database (Denmark)

    Borri, P.; Langbein, W.; Woggon, U.


    In this paper, the present status of the experimental study of the optical properties of biexcitons in semiconductor microcavities is reviewed. In particular, a detailed investigation of a polariton-biexciton transition in a high-quality single quantum well GaAs/AlGaAs microcavity is reported...

  12. Semiconductor Nanocrystal Photonics (United States)


    Hahn, H. Du, and T. D. Krauss, "Photoluminescence enhancement of colloidal semiconductor quantum dots embedded in a monolithic microcavity," Appl... DBRs ). The colloidal NC suspension was spun-coat into a 95-nm thick layer in the center of the cavity and then the other layers forming the top DBR

  13. Terahertz semiconductor nonlinear optics

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias


    nonlinearity in doped semiconductors originates from the near-instantaneous heating of free electrons in the ponderomotive potential created by electric field of the THz pulse, leading to ultrafast increase of electron effective mass by intervalley scattering. Modification of effective mass in turn leads...


    Directory of Open Access Journals (Sweden)

    M.B. Dutt


    Full Text Available Ion beam processing of materials in general and semiconductors in particular, started with ion implantation in semiconductors; first used by Ohl at Bell Labs in 1952 toimprove the electrical characteristics of silicon point contact diodes by implanting H, He, N and Ar ions.The improvement was obvious but it was caused by surface damage and notthe ion implantation. However, in the process, ion implantation had an entry and slowly it became popular among the scientists and the technocrats. Thus, over the last six decades, demands continued for new and improved materials and devices that has pushed ion implanter to expand to ion beam technology. In the semiconductor industry alone, the processes have evolved so much so that in today’s world, there are morethan 4000 ion implanters in the IC fab lines apart from otherion beam-assisted processing machines. Ion beam deposition techniques, ion beam lithography, ion beam etching, ion beammilling are all ion beam beam-assisted techniques that arebeing extensively used in semiconductor industries. In this backdrop, it was thought that a compilation of uses of allthese techniques together with relevant tools of analysis toserve as a guide to the semiconductor scientists and technologists for a glimpse of the ongoing efforts being madein this direction. Fortunately enough, Indian research is not lagging in use of all these modern day technologies that will be evident as the reader will go from one article to the other of this special volume.Defence Science Journal, 2009, 59(4, pp.328-328, DOI:

  15. Dot-array implantation for patterned doping of semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Wanzenboeck, H.D. [Institute f. Solid State Electronics, Vienna University of Technology, Floragasse 7, A-1040 Vienna (Austria)]. E-mail:; Ostermaier, C. [Institute f. Solid State Electronics, Vienna University of Technology, Floragasse 7, A-1040 Vienna (Austria); Gruen, A. [Institute f. Solid State Electronics, Vienna University of Technology, Floragasse 7, A-1040 Vienna (Austria); Eichinger, B. [Institute f. Solid State Electronics, Vienna University of Technology, Floragasse 7, A-1040 Vienna (Austria); Karner, M. [Institute f. Solid State Electronics, Vienna University of Technology, Floragasse 7, A-1040 Vienna (Austria); Bertagnolli, E. [Institute f. Solid State Electronics, Vienna University of Technology, Floragasse 7, A-1040 Vienna (Austria)


    Novel ion beam processing for microelectronic applications has been performed by doping silicon with a focused ion beam tool. A Ga{sup +} ion beam with a energy between 10 and 50 keV was used for p-doping of Si. The ion beam could be focused to an effective beam diameter in the sub-micron range with the smallest focus own below 10 nm. In contrast to conventional implantation with a broad ion beam where the doped area is assigned by a hardmask the implantation was achieved by scanning a focused ion beam over the designated implantation area. With this approach not only the hardmask becomes obsolete because of the electronic beam guidance. Moreover, different doses may be implanted on the same wafer. An additional feature is the inhomogeneous implantation in a pixel-array, where the distance between exposed pixels can be deliberately varied. Even single spots can be independently doped with the focused gallium beam. Due to lateral scattering of ions in the semiconductor the circular implantation area is larger than the beam diameter. With a variation of the pixel spacing we could intentionally obtain either a overlap or a separation of implantation spots. With a four-point method we have investigated the conductivity of the dot-array implanted area. The conductivity of the p-doped region could be deliberately scaled by varying the pixel spacing, the implantation dose and the ion energy. The effective implantation diameter of a single pixel could be determined. This modified implantation approach was also used to fabricate functional p-channel MOSFET's. The Ga implantation with a focused ion beam was used for p-doping of source and drain regions of the transistor device. The utilization of this dot-array implantation with a FIB for semiconductor circuitry demonstrates the potential application of this approach. With the laterally inhomogeneous implantation dot-arrays of doped zones in the nanometer range could be fabricated.

  16. Diode-pumped laser altimeter (United States)

    Welford, D.; Isyanova, Y.


    TEM(sub 00)-mode output energies up to 22.5 mJ with 23 percent slope efficiencies were generated at 1.064 microns in a diode-laser pumped Nd:YAG laser using a transverse-pumping geometry. 1.32-micron performance was equally impressive at 10.2 mJ output energy with 15 percent slope efficiency. The same pumping geometry was successfully carried forward to several complex Q-switched laser resonator designs with no noticeable degradation of beam quality. Output beam profiles were consistently shown to have greater than 90 percent correlation with the ideal TEM(sub 00)-order Gaussian profile. A comparison study on pulse-reflection-mode (PRM), pulse-transmission-mode (PTM), and passive Q-switching techniques was undertaken. The PRM Q-switched laser generated 8.3 mJ pulses with durations as short as 10 ns. The PTM Q-switch laser generated 5 mJ pulses with durations as short as 5 ns. The passively Q-switched laser generated 5 mJ pulses with durations as short as 2.4 ns. Frequency doubling of both 1.064 microns and 1.32 microns with conversion efficiencies of 56 percent in lithium triborate and 10 percent in rubidium titanyl arsenate, respectively, was shown. Sum-frequency generation of the 1.064 microns and 1.32 microns radiations was demonstrated in KTP to generate 1.1 mJ of 0.589 micron output with 11.5 percent conversion efficiency.

  17. Electronic structure of semiconductor-metal-semiconductor heterostructures (United States)

    Masri, Pierre

    For the first time, we present in this article a microscopic self-consistent theory of the electronic structure of semiconductor-metal-semiconductor (SMS) heterostructures. This is done within the framework of a tight-binding approximation. We use a one-band model and a simplified two-band model to describe metal and semiconductor bulk bands, respectively. Results are given for a material-symmetrical and interface-assymetrical SMS structure: this involves the same semiconductors, but different interface polarities (anion- and cation-like interfaces). These results include metal-like states (built-in metal band) and metal-induced semiconductor-like states. The relevance of the charge neutrality condition to this feature and to the determination of the position of the SMS Fermi level is discussed. We also emphasize the confining role of interfaces, with respect to semiconductor-like states, within the semiconductor gap.

  18. Optical processes in dilute nitrides Semiconductors; Alloys

    CERN Document Server

    Potter, R J


    This thesis is concerned with the narrow bandgap semiconductor alloys known as dilute nitrides. The initial part of this project was concerned with characterisation of chemical beam epitaxy (CBE) grown samples so that growth techniques could be refined. Early samples show evidence of structural/compositional disorder resulting from the large miscibility gap induced by nitrogen. Non-equilibrium growth was employed to overcome this, eventually resulting in improved material. In the second part of this project, steady-state and time-resolved photoluminescence, along with photomodulated reflectance were employed to investigate the optical properties of molecular beam epitaxy (MBE) grown GalnNAs, GaNAs and InGaAs quantum wells (QWs). Low temperature results show evidence of carrier localization, which was interpreted in terms of structural/compositional fluctuations induced by the nitrogen incorporation. Poor photoluminescence efficiency and rapid decay of emission kinetics indicate the presence of strong non-radi...

  19. Design of a CMOS Adaptive Charge Pump with Dynamic Current Matching

    Institute of Scientific and Technical Information of China (English)


    A novel structure for a charge pump circuit is proposed, in which the charge-pump (CP) current can adaptively regulated according to phase-locked loops (PLL) frequency synthesis demand. The current follow technology is used to make perfect current matching characteristics, and the two differential inverters are implanted to increase the speed of charge pump and decrease output spur due to theory of low voltage difference signal. Simulation results, with 1st silicon 0.25 μm 2.5 V complementary metal-oxide-semiconductor (CMOS) mixed-signal process, show the good current matching characteristics regardless of the charge pump output voltages.

  20. High-Resolution Differential Thermography of Semiconductor Edifices

    Directory of Open Access Journals (Sweden)

    Vera Marie Sastine


    Full Text Available We develop a cost-effective, high-resolution, and noninvasive imaging technique for thermal mapping of semiconductor edifices in integrated circuits. Initial implementation was done using a power-stabilized optical feedback laser system that detects changes in the optical beam-induced current when the package temperature of the device is increased. The linear change in detected current can be translated to a thermal gradient, which can reveal semiconductor “hotspots”—localized sites with anomalous thermal activity. These locales are possible fault sites or areas susceptible to defects, which are the best jump-off points for failure analysis.

  1. Semiconductor lasers as integrated optical biosensors: sensitivity optimisation

    Energy Technology Data Exchange (ETDEWEB)

    Coote, J; Sweeney, S J [Advanced Technology Institute, University of Surrey, Guildford, UK GU2 7XH (United Kingdom)


    Semiconductor lasers contain both a light source and waveguide, rendering them suitable for adaptation to evanescent field biosensing. One-dimensional simulations using the beam propagation method have been carried out for planar semiconductor waveguide structures, with a view to maximising sensitivity of the effective index to changes in the refractive index and thickness of a film on the waveguide surface. Various structural parameters are investigated and it is found that thinning the upper cladding layer maximises the sensitivity. Implications for laser operation are considered, and an optimised structure is proposed. Surface layer index and thickness resolutions of 0.2 and 2nm are predicted.

  2. Growth and Defect Characterization of Quantum Dot-Embedded III-V Semiconductors for Advanced Space Photovoltaics (United States)


    intermediate band, quantum dots, metamorphic III-V semiconductors, virtual substrates, defect spectroscopy, molecular beam epitaxy 16. SECURITY...AFRL-RV-PS- AFRL-RV-PS- TR-2014-0059 TR-2014-0059 GROWTH AND DEFECT CHARACTERIZATION OF QUANTUM DOT-EMBEDDED III-V SEMICONDUCTORS FOR ADVANCED...COVERED (From - To) 2 4 May 2012 – 06 Mar 2014 4. TITLE AND SUBTITLE Growth and Defect Characterization of Quantum Dot-Embedded III-V Semiconductors

  3. Pump-Controlled Modal Interactions in Microdisk Lasers

    CERN Document Server

    Liew, Seng Fatt; Redding, Brandon; Solomon, Glenn S; Cao, Hui


    We demonstrate an effective control of nonlinear interactions of lasing modes in a semiconductor microdisk cavity by shaping the pump profile. A target mode is selected at the expense of its competing modes either by increasing their lasing thresholds or suppressing their power slopes above the lasing threshold. Despite of strong spatial overlap of the lasing modes at the disk boundary, adaptive pumping enables an efficient selection of any lasing mode to be the dominant one, leading to a switch of lasing frequency. The theoretical analysis illustrates both linear and nonlinear effects of selective pumping, and quantify their contributions to lasing mode selection. This work shows that adaptive pumping not only provides a powerful tool of controlling the nonlinear process in multimode lasers, but also enables the tuning of lasing characteristic after the lasers have been fabricated.

  4. Simple highly efficient pumping configuration in high-power thin-disk laser (United States)

    Seyedzamani, Sasan; Eslami, Esmaeil


    A simple high-power thin-disk pumping configuration using a radiation combination of four commercially available laser-diode stacks is introduced. Two setup modifications are presented to compensate the nonsuitable shape of the pumping spot arising from low beam quality in our combination method. The effects of setup modifications on pumping spot shapes are confirmed by ray tracing simulations using Trace-pro™ software. All setups are arranged in the laboratory, and the experimental measurements show pumping spots improvements on the disk due to modifications in agreement with simulation results. Output power measurements show that by adapting the pumping spot size to the disk cooling capacity the modified setups can deliver higher output powers and efficiencies. Furthermore, the modifications reduce the laser threshold and improve output laser beam quality. Hence, the modifications make the simple four laser-diodes beam combination applicable for thin-disk laser pumping.

  5. Nanoelectronics in oxides and semiconductors (United States)

    Cheng, Guanglei

    The success of silicon industry lies on three major properties of silicon, an easily formed oxide layer to allow field effect operation, tunability of carrier density and high device scalability. All these features exist in oxides, together with some novel properties such as ferroelectricity, magnetic effects and metal-insulator transition. With the recent development in material growth method including molecular beam epitaxy (MBE), pulsed laser deposition (PLD) and reflection high energy electron diffraction (REED), atomically engineered oxide interfaces become available, thus opening the door to the novel oxide nanoelectronics. In this dissertation we create and study nanoelectronics in oxides, semiconductors and hybrid of these two. We used a conductive atomic force microscope tip to write single electron transistors in the 3-unit-cell-LaAlO 3/SrTiO3 heterostructure and observed ferroelectric tunneling behaviors. We also fabricated ferroelectric field transistors directly on silicon using strained SrTiO3 ferroelectric film and further confirmed the ferroelectric properties of this device. Meanwhile, we developed an ultrasensitive microwave capacitance sensor to study the electronic properties of self-assembled quantum dots and the switching mechanism of memristive devices. The integration of this sensor to a home made atomic force microscope provides an important tool to study the dielectric properties at nanoscale.

  6. 抽油机智能间抽节能控制系统研究%Research on Intelligent Inter-drilling and Saving Energy Control System of the Beam Pumping Unit

    Institute of Scientific and Technical Information of China (English)

    高升; 张力; 张凯


    为稳定产量、降低能耗、提高系统效率和减少抽油机的维修费用,设计了一种抽油机智能间抽节能控制系统,以控制抽油机合理间抽为主要任务,即采用多种传感器采集油井信息,通过微处理器对抽油机井动态供液状况进行判断,同时结合新型的油井生产供排关系理论和液面变化规律,动态的选取抽油机的间抽标准和启停时间,运用对比优化的方法,更加有效地控制抽油机的启停,经过实验测试,达到了节约能源和智能化控制目的.%In order to keep production stable, reduce energy consumption, improve the efficiency of the system,and cut down the maintenance cost of the pumping units, an intelligent inter - drilling control system of the pumping unit has been designed in this paper. The main task of the system is keeping the inter - drilling rational. It collects oil well information with kinds of sensors, and estimates the fluid dynamic conditions of pumping wells by means of the microprocessor. Meanwhile, combining with the latest theory of supply - discharge balance of oil well production and the changing rules of liquid level, applying the method of contrast optimization,it can control the stop - start of the pumping unit more effectively than before. Experimental tests have proved that the system meets the goals of saving energy and intelligent control.

  7. Formation and all-optical control of optical patterns in semiconductor microcavities (United States)

    Binder, R.; Tsang, C. Y.; Tse, Y. C.; Luk, M. H.; Kwong, N. H.; Chan, Chris K. P.; Leung, P. T.; Lewandowski, P.; Schumacher, Stefan; Lafont, O.; Baudin, E.; Tignon, J.


    Semiconductor microcavities offer a unique way to combine transient all-optical manipulation of GaAs quantum wells with the benefits of structural advantages of microcavities. In these systems, exciton-polaritons have dispersion relations with very small effective masses. This has enabled prominent effects, for example polaritonic Bose condensation, but it can also be exploited for the design of all-optical communication devices. The latter involves non-equilibrium phase transitions in the spatial arrangement of exciton-polaritons. We consider the case of optical pumping with normal incidence, yielding a spatially homogeneous distribution of exciton-polaritons in optical cavities containing the quantum wells. Exciton-exciton interactions can trigger instabilities if certain threshold behavior requirements are met. Such instabilities can lead, for example, to the spontaneous formation of hexagonal polariton lattices (corresponding to six-spot patterns in the far field), or to rolls (corresponding to two-spot far field patterns). The competition among these patterns can be controlled to a certain degree by applying control beams. In this paper, we summarize the theory of pattern formation and election in microcavities and illustrate the switching between patterns via simulation results.

  8. Polymer semiconductor crystals

    Directory of Open Access Journals (Sweden)

    Jung Ah Lim


    Full Text Available One of the long-standing challenges in the field of polymer semiconductors is to figure out how long interpenetrating and entangled polymer chains self-assemble into single crystals from the solution phase or melt. The ability to produce these crystalline solids has fascinated scientists from a broad range of backgrounds including physicists, chemists, and engineers. Scientists are still on the hunt for determining the mechanism of crystallization in these information-rich materials. Understanding the theory and concept of crystallization of polymer semiconductors will undoubtedly transform this area from an art to an area that will host a bandwagon of scientists and engineers. In this article we describe the basic concept of crystallization and highlight some of the advances in polymer crystallization from crystals to nanocrystalline fibers.

  9. Stretchable Organic Semiconductor Devices. (United States)

    Qian, Yan; Zhang, Xinwen; Xie, Linghai; Qi, Dianpeng; Chandran, Bevita K; Chen, Xiaodong; Huang, Wei


    Stretchable electronics are essential for the development of intensely packed collapsible and portable electronics, wearable electronics, epidermal and bioimplanted electronics, 3D surface compliable devices, bionics, prosthesis, and robotics. However, most stretchable devices are currently based on inorganic electronics, whose high cost of fabrication and limited processing area make it difficult to produce inexpensive, large-area devices. Therefore, organic stretchable electronics are highly attractive due to many advantages over their inorganic counterparts, such as their light weight, flexibility, low cost and large-area solution-processing, the reproducible semiconductor resources, and the easy tuning of their properties via molecular tailoring. Among them, stretchable organic semiconductor devices have become a hot and fast-growing research field, in which great advances have been made in recent years. These fantastic advances are summarized here, focusing on stretchable organic field-effect transistors, light-emitting devices, solar cells, and memory devices.

  10. Compound semiconductor device modelling

    CERN Document Server

    Miles, Robert


    Compound semiconductor devices form the foundation of solid-state microwave and optoelectronic technologies used in many modern communication systems. In common with their low frequency counterparts, these devices are often represented using equivalent circuit models, but it is often necessary to resort to physical models in order to gain insight into the detailed operation of compound semiconductor devices. Many of the earliest physical models were indeed developed to understand the 'unusual' phenomena which occur at high frequencies. Such was the case with the Gunn and IMPATI diodes, which led to an increased interest in using numerical simulation methods. Contemporary devices often have feature sizes so small that they no longer operate within the familiar traditional framework, and hot electron or even quantum­ mechanical models are required. The need for accurate and efficient models suitable for computer aided design has increased with the demand for a wider range of integrated devices for operation at...

  11. Semiconductor physics an introduction

    CERN Document Server

    Seeger, Karlheinz


    Semiconductor Physics - An Introduction - is suitable for the senior undergraduate or new graduate student majoring in electrical engineering or physics. It will also be useful to solid-state scientists and device engineers involved in semiconductor design and technology. The text provides a lucid account of charge transport, energy transport and optical processes, and a detailed description of many devices. It includes sections on superlattices and quantum well structures, the effects of deep-level impurities on transport, the quantum Hall effect and the calculation of the influence of a magnetic field on the carrier distribution function. This 6th edition has been revised and corrected, and new sections have been added to different chapters.

  12. Single frequency semiconductor lasers

    CERN Document Server

    Fang, Zujie; Chen, Gaoting; Qu, Ronghui


    This book systematically introduces the single frequency semiconductor laser, which is widely used in many vital advanced technologies, such as the laser cooling of atoms and atomic clock, high-precision measurements and spectroscopy, coherent optical communications, and advanced optical sensors. It presents both the fundamentals and characteristics of semiconductor lasers, including basic F-P structure and monolithic integrated structures; interprets laser noises and their measurements; and explains mechanisms and technologies relating to the main aspects of single frequency lasers, including external cavity lasers, frequency stabilization technologies, frequency sweeping, optical phase locked loops, and so on. It paints a clear, physical picture of related technologies and reviews new developments in the field as well. It will be a useful reference to graduate students, researchers, and engineers in the field.

  13. Three dimensional strained semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Voss, Lars; Conway, Adam; Nikolic, Rebecca J.; Leao, Cedric Rocha; Shao, Qinghui


    In one embodiment, an apparatus includes a three dimensional structure comprising a semiconductor material, and at least one thin film in contact with at least one exterior surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the three dimensional structure. In another embodiment, a method includes forming a three dimensional structure comprising a semiconductor material, and depositing at least one thin film on at least one surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the structure.

  14. Self- Balanced Charge Pump with Fast Lock Circuit

    Institute of Scientific and Technical Information of China (English)

    JIANG Xiang; ZOU Xuecheng; XIAO Dingzhong; LIU Sanqing


    A self-balanced charge pump (CP) with fast lock circuit to achieve nearly zero phase error is proposed and analyzed. The proposed CP is designed based on the SMIC 0.25 μm 1P5M complementary metal-oxide semiconductor (CMOS) process with a 2.5 V supply voltage. HSPICE simulation shows that even if the mismatch of phase/frequency detector (PFD) was beyond 10%, the charge pump could still keep nearly zero phase error. Incorporated fast lock circuit can shorten start-up time to below 300 ns.

  15. High-power diode-pumped AlGaAs surface-emitting laser. (United States)

    Holm, M A; Burns, D; Cusumano, P; Ferguson, A I; Dawson, M D


    We report the development and characterization of an efficient diode-pumped surface-emitting semiconductor laser operating at approximately 870 nm. By using a semiconductor Bragg reflector stack/multiple GaAs quantum well structure, mounted within a conventional laser cavity, we achieved single transverse mode laser output powers of 153 mW. Self-tuning over a 15-nm spectral range has been obtained.

  16. Generation of the Stigmatic Beam with Orbital Angular Momentum

    Institute of Scientific and Technical Information of China (English)

    高春清; 魏光辉; Horst WEBER


    The stigmatic beam with orbital angular momentum is generated by transforming the Hermite-Gaussian beamof a diode-pumped Nd:YAG laser through a rotated cylindrical optical system. Behind the transformation optics,the output beam has an intensity distribution of ring shape and a twist phase. The beam transformation istheoretically calculated and the result has been confirmed in the experiments.

  17. Initial Tests of a Plasma Beam Combiner at NIF (United States)

    Kirkwood, R. K.; Turnbull, D. P.; Chapman, T. D.; Wilks, S. C.; London, R. A.; Berger, R. L.; Michel, P. A.; Divol, L.; Dunlop, W. H.; MacGowan, B. J.; Fournier, K. B.; Blue, B. E.; NIF Team


    The seeded forward SBS process that is known to effectively amplify beams in ignition targets has recently been used to design and test a target to combine the power and energy of many beams of the NIF facility into a single beam by intersecting them in an ionized gas. The demand for high-power beams for a variety of applications at NIF makes a demonstration of this process attractive. We will describe experiments using a gas-filled balloon heated by 10 quads of beams, and pumped by additional frequency-tuned quads to amplify a single beam. The beam energy is indicated by gated x-ray images of both the spots produced by the transmitted pump and probe beams and the spot produced by a non-interacting quad of beams when they terminate on a foil. The first experiment produced a high brightness seed beam with significant reductions in brightness of the pumping beams, consistent with their depletion by energy transfer to the seed. Additional experiments studying spot brightness with varying pump power to determine total delivered seed beam energy and power will be discussed as available. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  18. Square shaped flat-top beam in refractive beam shapers (United States)

    Laskin, Alexander; Laskin, Vadim; Ostrun, Aleksei


    Lossless transformation of round Gaussian to square shaped flat-top collimated beam is important in building highpower solid state laser systems to improve optical pumping or amplification. There are industrial micromachining applications like scribing, display repair, which performance is improved when a square shaped spot with uniform intensity is created. Proved beam shaping solutions to these techniques are refractive field mapping beam shapers having some important features: flatness of output phase front, small output divergence, high transmittance, extended depth of field, operation with TEM00 and multimode lasers. Usual approach to design refractive beam shapers implies that input and output beams have round cross-section, therefore the only way to create a square shaped output beam is using a square mask, which leads to essential losses. When an input laser beam is linearly polarized it is suggested to generate square shaped flat-top output by applying beam shaper lenses from birefringent materials or by using additional birefringent components. Due to birefringence there is introduced phase retardation in beam parts and is realized a square shaped interference pattern at the beam shaper output. Realization of this approach requires small phase retardation, therefore weak birefringence effect is enough and birefringent optical components, operating in convergent or divergent beams, can be made from refractive materials, which crystal optical axis is parallel to optical axis of entire beam shaper optical system. There will be considered design features of beam shapers creating square shaped flat-top beams. Examples of real implementations and experimental results will be presented as well.

  19. Semiconductors for organic transistors


    Antonio Facchetti


    Organic molecules/polymers with a π-conjugated (hetero)aromatic backbone are capable of transporting charge and interact efficiently with light. Therefore, these systems can act as semiconductors in opto-electronic devices similar to inorganic materials. However, organic chemistry offers tools for tailoring materials' functional properties via modifications of the molecular/monomeric units, opening new possibilities for inexpensive device manufacturing. This article reviews the fundamental as...

  20. Doping of organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Luessem, B.; Riede, M.; Leo, K. [Institut fuer Angewandte Photophysik, TU Dresden (Germany)


    The understanding and applications of organic semiconductors have shown remarkable progress in recent years. This material class has been developed from being a lab curiosity to the basis of first successful products as small organic LED (OLED) displays; other areas of application such as OLED lighting and organic photovoltaics are on the verge of broad commercialization. Organic semiconductors are superior to inorganic ones for low-cost and large-area optoelectronics due to their flexibility, easy deposition, and broad variety, making tailor-made materials possible. However, electrical doping of organic semiconductors, i.e. the controlled adjustment of Fermi level that has been extremely important to the success of inorganic semiconductors, is still in its infancy. This review will discuss recent work on both fundamental principles and applications of doping, focused primarily to doping of evaporated organic layers with molecular dopants. Recently, both p- and n-type molecular dopants have been developed that lead to efficient and stable doping of organic thin films. Due to doping, the conductivity of the doped layers increases several orders of magnitude and allows for quasi-Ohmic contacts between organic layers and metal electrodes. Besides reducing voltage losses, doping thus also gives design freedom in terms of transport layer thickness and electrode choice. The use of doping in applications like OLEDs and organic solar cells is highlighted in this review. Overall, controlled molecular doping can be considered as key enabling technology for many different organic device types that can lead to significant improvements in efficiencies and lifetimes. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Semiconductor Ion Implanters (United States)

    MacKinnon, Barry A.; Ruffell, John P.


    In 1953 the Raytheon CK722 transistor was priced at 7.60. Based upon this, an Intel Xeon Quad Core processor containing 820,000,000 transistors should list at 6.2 billion! Particle accelerator technology plays an important part in the remarkable story of why that Intel product can be purchased today for a few hundred dollars. Most people of the mid twentieth century would be astonished at the ubiquity of semiconductors in the products we now buy and use every day. Though relatively expensive in the nineteen fifties they now exist in a wide range of items from high-end multicore microprocessors like the Intel product to disposable items containing `only' hundreds or thousands like RFID chips and talking greeting cards. This historical development has been fueled by continuous advancement of the several individual technologies involved in the production of semiconductor devices including Ion Implantation and the charged particle beamlines at the heart of implant machines. In the course of its 40 year development, the worldwide implanter industry has reached annual sales levels around 2B, installed thousands of dedicated machines and directly employs thousands of workers. It represents in all these measures, as much and possibly more than any other industrial application of particle accelerator technology. This presentation discusses the history of implanter development. It touches on some of the people involved and on some of the developmental changes and challenges imposed as the requirements of the semiconductor industry evolved.

  2. Survey of semiconductor physics

    CERN Document Server

    Böer, Karl W


    Any book that covers a large variety of subjects and is written by one author lacks by necessity the depth provided by an expert in his or her own field of specialization. This book is no exception. It has been written with the encouragement of my students and colleagues, who felt that an extensive card file I had accumulated over the years of teaching solid state and semiconductor physics would be helpful to more than just a few of us. This file, updated from time to time, contained lecture notes and other entries that were useful in my research and permitted me to give to my students a broader spectrum of information than is available in typical textbooks. When assembling this material into a book, I divided the top­ ics into material dealing with the homogeneous semiconductor, the subject of the previously published Volume 1, and the inhomoge­ neous semiconductor, the subject of this Volume 2. In order to keep the book to a manageable size, sections of tutorial character which can be used as text for a g...

  3. Properties of cat mutually pumped phase conjugation and two-wave mixing gain in doped KNSBN

    Institute of Scientific and Technical Information of China (English)

    Xinguang Xu(许心光); Zongshu Shao(邵宗书); Zhengping Wang(王正平); Junhai Liu(刘均海); Guibao Xu(许贵宝); Dawei Hu(胡大伟)


    Cat mutually pumped phase conjugation configuration is discovered and investigated by using two-wavemixing in (KyNa1-y)2z(SrxBa1-x)1-zNb2O6 (KNSBN) crystal. When only one signal or pumped beamdoes not give birth to phase conjugation, the maximum reflectivity of signal and pumped beam attain140% and 30% due to two-wave mixing, respectively. The experimental results show that the two-wavemixing can reduce the threshold of incident beams power, extend the incident angle range, and shortenresponse rate in the process of self-pumped phase conjugator (SPPC) in KNSBN crystal.

  4. Electron beam direct write: shaped beam overcomes resolution concerns (United States)

    Stolberg, Ines; Pain, Laurent; Kretz, Johannes; Boettcher, Monika; Doering, Hans-Joachim; Gramss, Juergen; Hahmann, Peter


    In semiconductor industry time to market is one of the key success factors. Therefore fast prototyping and low-volume production will become extremely important for developing process technologies that are well ahead of the current technological level. Electron Beam Lithography has been launched for industrial use as a direct write technology for these types of applications. However, limited throughput rates and high tool complexity have been seen as the major concerns restricting the industrial use of this technology. Nowadays this begins to change. Variable Shaped Beam (VSB) writers have been established in Electron Beam Direct Write (EBDW) on Si or GaAs. In the paper semiconductor industry requirements to EBDW will be outlined. Behind this background the Vistec SB3050 lithography system will be reviewed. The achieved resolution enhancement of the VSB system down to the 22nm node exposure capability will be discussed in detail; application examples will be given. Combining EBDW in a Mix and Match technology with optical lithography is one way to utilize the high flexibility advantage of this technology and to overcome existing throughput concerns. However, to some extend a common Single Electron Beam Technology (SBT) will always be limited in throughput. Therefore Vistec's approach of a system that is based on the massive parallelisation of beams (MBT), which was initially pursued in a European Project, will also be discussed.

  5. Study of the emission spectra of a 1320-nm semiconductor disk laser and its second harmonic (United States)

    Gochelashvili, K. S.; Derzhavin, S. I.; Evdokimova, O. N.; Zolotovskii, I. O.; Podmazov, S. V.


    The spectral characteristics of an optically pumped external-cavity semiconductor disk laser near λ = 1320 nm are studied experimentally. Intracavity second harmonic generation is obtained using an LBO nonlinear crystal. The output power at a wavelength of 660 nm in the cw regime was 620 mW, and the peak power in the pulsed regime was 795 mW.

  6. Semiconductor optoelectronic devices for free-space optical communications (United States)

    Katz, J.


    The properties of individual injection lasers are reviewed, and devices of greater complexity are described. These either include or are relevant to monolithic integration configurations of the lasers with their electronic driving circuitry, power combining methods of semiconductor lasers, and electronic methods of steering the radiation patterns of semiconductor lasers and laser arrays. The potential of AlGaAs laser technology for free-space optical communications systems is demonstrated. These solid-state components, which can generate and modulate light, combine the power of a number of sources and perform at least part of the beam pointing functions. Methods are proposed for overcoming the main drawback of semiconductor lasers, that is, their inability to emit the needed amount of optical power in a single-mode operation.

  7. Detection of pump degradation

    Energy Technology Data Exchange (ETDEWEB)

    Greene, R.H.; Casada, D.A.; Ayers, C.W. [and others


    This Phase II Nuclear Plant Aging Research study examines the methods of detecting pump degradation that are currently employed in domestic and overseas nuclear facilities. This report evaluates the criteria mandated by required pump testing at U.S. nuclear power plants and compares them to those features characteristic of state-of-the-art diagnostic programs and practices currently implemented by other major industries. Since the working condition of the pump driver is crucial to pump operability, a brief review of new applications of motor diagnostics is provided that highlights recent developments in this technology. The routine collection and analysis of spectral data is superior to all other technologies in its ability to accurately detect numerous types and causes of pump degradation. Existing ASME Code testing criteria do not require the evaluation of pump vibration spectra but instead overall vibration amplitude. The mechanical information discernible from vibration amplitude analysis is limited, and several cases of pump failure were not detected in their early stages by vibration monitoring. Since spectral analysis can provide a wealth of pertinent information concerning the mechanical condition of rotating machinery, its incorporation into ASME testing criteria could merit a relaxation in the monthly-to-quarterly testing schedules that seek to verify and assure pump operability. Pump drivers are not included in the current battery of testing. Operational problems thought to be caused by pump degradation were found to be the result of motor degradation. Recent advances in nonintrusive monitoring techniques have made motor diagnostics a viable technology for assessing motor operability. Motor current/power analysis can detect rotor bar degradation and ascertain ranges of hydraulically unstable operation for a particular pump and motor set. The concept of using motor current or power fluctuations as an indicator of pump hydraulic load stability is presented.

  8. Controlling the Goos-Hänchen and Imbert-Fedorov shifts via pump and driving fields (United States)

    Asiri, Saeed; Xu, Jingping; Al-Amri, M.; Zubairy, M. Suhail


    We consider a three-level atomic medium and discuss how to control the Goos-Hänchen (longitudinal) and Imbert-Fedorov (transverse) shifts for a circular polarized Gaussian beam via a pump field and a coherent driving field applied to the atomic medium. The susceptibility of the atomic medium can be adjusted by changing the driving and pump fields. Consequently, for a fixed driving field, by turning on and off the pump field the amplitude and the direction of the longitudinal and transverse shifts of such beam can be changed. We adopt stationary phase and beam simulation methods to derive our results.

  9. Efficient and high-power green beam generation by frequency doubling of acousto-optic Q-switched diode-side pumped Nd:YAG rod laser in a coupled cavity

    Indian Academy of Sciences (India)

    S K Sharma; A J Singh; P K Mukhopadhyay; S M Oak


    A 52-W green laser at 532 nm by extra-cavity second-harmonic generation in a coupled-cavity configuration is demonstrated. The fundamental laser is a diode-side-pumped acousto-optic (AO) Q-switched Nd:YAG rod laser producing 84 W of average power at 1064 nm at 8 kHz repetition rate. Type-II phase-matched polished KTP crystal is used as the nonlinear crystal for second-harmonic generation. The individual green pulse width is 50 ns and the fundamental to second harmonic conversion efficiency is 61.8%.

  10. Detection of pump degradation

    Energy Technology Data Exchange (ETDEWEB)

    Casada, D. [Oak Ridge National Lab., TN (United States)


    There are a variety of stressors that can affect the operation of centrifugal pumps. Although these general stressors are active in essentially all centrifugal pumps, the stressor level and the extent of wear and degradation can vary greatly. Parameters that affect the extent of stressor activity are manifold. In order to assure the long-term operational readiness of a pump, it is important to both understand the nature and magnitude of the specific degradation mechanisms and to monitor the performance of the pump. The most commonly applied method of monitoring the condition of not only pumps, but rotating machinery in general, is vibration analysis. Periodic or continuous special vibration analysis is a cornerstone of most pump monitoring programs. In the nuclear industry, non-spectral vibration monitoring of safety-related pumps is performed in accordance with the ASME code. Pump head and flow rate are also monitored, per code requirements. Although vibration analysis has dominated the condition monitoring field for many years, there are other measures that have been historically used to help understand pump condition; advances in historically applied technologies and developing technologies offer improved monitoring capabilities. The capabilities of several technologies (including vibration analysis, dynamic pressure analysis, and motor power analysis) to detect the presence and magnitude of both stressors and resultant degradation are discussed.

  11. Optically pumped atoms

    CERN Document Server

    Happer, William; Walker, Thad


    Covering the most important knowledge on optical pumping of atoms, this ready reference is backed by numerous examples of modelling computation for optical pumped systems. The authors show for the first time that modern scientific computing software makes it practical to analyze the full, multilevel system of optically pumped atoms. To make the discussion less abstract, the authors have illustrated key points with sections of MATLAB codes. To make most effective use of contemporary mathematical software, it is especially useful to analyze optical pumping situations in the Liouville spa

  12. Champagne Heat Pump (United States)

    Jones, Jack A.


    The term champagne heat pump denotes a developmental heat pump that exploits a cycle of absorption and desorption of carbon dioxide in an alcohol or other organic liquid. Whereas most heat pumps in common use in the United States are energized by mechanical compression, the champagne heat pump is energized by heating. The concept of heat pumps based on other absorption cycles energized by heat has been understood for years, but some of these heat pumps are outlawed in many areas because of the potential hazards posed by leakage of working fluids. For example, in the case of the water/ammonia cycle, there are potential hazards of toxicity and flammability. The organic-liquid/carbon dioxide absorption/desorption cycle of the champagne heat pump is similar to the water/ammonia cycle, but carbon dioxide is nontoxic and environmentally benign, and one can choose an alcohol or other organic liquid that is also relatively nontoxic and environmentally benign. Two candidate nonalcohol organic liquids are isobutyl acetate and amyl acetate. Although alcohols and many other organic liquids are flammable, they present little or no flammability hazard in the champagne heat pump because only the nonflammable carbon dioxide component of the refrigerant mixture is circulated to the evaporator and condenser heat exchangers, which are the only components of the heat pump in direct contact with air in habitable spaces.

  13. Resonance wave pumping: wave mass transport pumping (United States)

    Carmigniani, Remi; Violeau, Damien; Gharib, Morteza


    It has been previously reported that pinching at intrinsic resonance frequencies a valveless pump (or Liebau pump) results in a strong pulsating flow. A free-surface version of the Liebau pump is presented. The experiment consists of a closed tank with a submerged plate separating the water into a free-surface and a recirculation section connected through two openings at each end of the tank. A paddle is placed at an off-centre position at the free-surface and controlled in a heaving motion with different frequencies and amplitudes. Near certain frequencies identified as resonance frequencies through a linear potential theory analysis, the system behaves like a pump. Particle Image Velocimetry (PIV) is performed in the near free surface region and compared with simulations using Volume of Fluid (VOF) method. The mean eulerian mass flux field (ρ) is extracted. It is observed that the flow is located in the vicinity of the surface layer suggesting Stokes Drift (or Wave Mass Transport) is the source of the pumping. A model is developped to extend the linear potential theory to the second order to take into account these observations. The authors would like to acknowledge the Gordon and Betty Moore Foundation for their generous support.

  14. Diode-pumped Yb3+:KYF4 femtosecond laser. (United States)

    Coluccelli, Nicola; Galzerano, Gianluca; Tonelli, Mauro; Laporta, Paolo; Svelto, Orazio


    Passive mode locking of a diode-pumped Yb(3+):KYF(4) laser is demonstrated using a semiconductor saturable absorber mirror. A high-stability, transform-limited pulse train with a repetition rate of 57 MHz is generated. Solitonlike pulses with maximum average output power of 250 mW, minimum pulse duration of 170 fs, and rms time jitter of 360 fs were obtained.

  15. OLET architectures for electrically-pumped organic lasers (United States)

    Zamboni, R.; Capelli, R.; Toffanin, S.; Murgia, M.; Först, M.; Muccini, M.


    Organic light emitting transistors (OLET) have been recently demonstrated as innovative architectures combining into an integrated optoelectronic device multi-functional properties namely, the driving ability of a transistor device with the conversion of electrical current into efficient light emission via electronic relaxation of organic semiconductors. State of the art materials, achievement and performances will be presented and discussed in view of possible OLET architectures exploitation as electrically pumped organic nanolasers.

  16. Self-mode-locking semiconductor disk laser. (United States)

    Gaafar, Mahmoud; Richter, Philipp; Keskin, Hakan; Möller, Christoph; Wichmann, Matthias; Stolz, Wolfgang; Rahimi-Iman, Arash; Koch, Martin


    The development of mode-locked semiconductor disk lasers received striking attention in the last 14 years and there is still a vast potential of such pulsed lasers to be explored and exploited. While for more than one decade pulsed operation was strongly linked to the employment of a saturable absorber, self-mode-locking emerged recently as an effective and novel technique in this field - giving prospect to a reduced complexity and improved cost-efficiency of such lasers. In this work, we highlight recent achievements regarding self-mode-locked semiconductor devices. It is worth to note, that although nonlinear effects in the active medium are expected to give rise to self-mode-locking, this has to be investigated with care in future experiments. However, there is a controversy whether results presented with respect to self-mode-locking truly show mode-locking. Such concerns are addressed in this work and we provide a clear evidence of mode-locking in a saturable-absorber-free device. By using a BBO crystal outside the cavity, green light originating from second-harmonic generation using the out-coupled laser beam is demonstrated. In addition, long-time-span pulse trains as well as radiofrequency-spectra measurements are presented for our sub-ps pulses at 500 MHz repetition rate which indicate the stable pulse operation of our device. Furthermore, a long-time-span autocorrelation trace is introduced which clearly shows absence of a pedestal or double pulses. Eventually, a beam-profile measurement reveals the excellent beam quality of our device with an M-square factor of less than 1.1 for both axes, showing that self-mode-locking can be achieved for the fundamental transverse mode.

  17. Demanding pump power; Krevende pumpekraft

    Energy Technology Data Exchange (ETDEWEB)

    Lie, Oeyvind


    The potential for pump power in Norway is huge, but it is difficult to exploit it. Norway has some pumping plants, but these are built for seasonal pumping (pumping up to the magazine in the summer, and production in the winter). Pump power plants for short periods do not exist in Norway. (AG)

  18. Molecular beam epitaxy a short history

    CERN Document Server

    Orton, J W


    This volume describes the development of molecular beam epitaxy from its origins in the 1960s through to the present day. It begins with a short historical account of other methods of crystal growth, both bulk and epitaxial, to set the subject in context, emphasising the wide range of semiconductor materials employed. This is followed by an introduction to molecular beams and their use in the Stern-Gerlach experiment and the development of the microwave MASER.

  19. White Light Pump-Probe Photothermal Mirror Spectrophotometer (United States)

    Hlaing, May; Marcano, Aristides


    We develop a new kind of spectrophotometer based on the photothermal mirror effect. The absorption of a focused tunable pump light by first atomic layers of the sample's surface generates a nanometric surface distortion or bump of thermal origin. A probe beam of light of fixed wavelength and with spot dimensions much larger than the pump beam's spot is used to test this thermal distortion. Changes in the wave-front of the reflected probe beam yields changes of the diffraction pattern of the reflected beam at the far field which can be used to produce a signal proportional to the amount of released heat. Tuning of the wavelength of the pump field generates a photothermal mirror spectrum. As tunable pump source we use the light from a Xenon arc-lamp filtered using a series of interference filter. This way we generate tunable pump light in the spectral region of 370-730 nm with a HWHM of 5 nm and power density of the order of tens of microwatts per nanometer. We obtain photothermal mirror spectra of metallic surfaces and other non-transparent samples. We show that these spectra are fundamentally different from the usual reflectance spectra which measure the percentage of the total of the total energy reflected by the surface.

  20. Pump element for a tube pump

    DEFF Research Database (Denmark)


    relative to the rod element so as to allow for a fluid flow in the tube through the first valve member, along the rod element, and through the second valve member. The tube comprises an at least partly flexible tube portion between the valve members such that a repeated deformation of the flexible tube...... portion acts to alternately close and open the valve members thereby generating a fluid flow through the tube. The invention further relates to a pump element comprising at least two non-return valve members connected by a rod element, and for insertion in an at least partly flexible tube in such tube...... pump as mentioned above, thereby acting to generate a fluid flow through the tube upon repeated deformation of the tube between the two valve members. The pump element may comprise a connecting part for coupling to another tube and may comprise a sealing part establishing a fluid tight connection...

  1. Method of passivating semiconductor surfaces (United States)

    Wanlass, Mark W.


    A method of passivating Group III-V or II-VI semiconductor compound surfaces. The method includes selecting a passivating material having a lattice constant substantially mismatched to the lattice constant of the semiconductor compound. The passivating material is then grown as an ultrathin layer of passivating material on the surface of the Group III-V or II-VI semiconductor compound. The passivating material is grown to a thickness sufficient to maintain a coherent interface between the ultrathin passivating material and the semiconductor compound. In addition, a device formed from such method is also disclosed.

  2. Electrodes for Semiconductor Gas Sensors. (United States)

    Lee, Sung Pil


    The electrodes of semiconductor gas sensors are important in characterizing sensors based on their sensitivity, selectivity, reversibility, response time, and long-term stability. The types and materials of electrodes used for semiconductor gas sensors are analyzed. In addition, the effect of interfacial zones and surface states of electrode-semiconductor interfaces on their characteristics is studied. This study describes that the gas interaction mechanism of the electrode-semiconductor interfaces should take into account the interfacial zone, surface states, image force, and tunneling effect.

  3. Ionization annealing of semiconductor crystals. Part two: the experiment

    Directory of Open Access Journals (Sweden)

    Garkavenko A. S.


    Full Text Available There is a conception that irradiation of semiconductor crystals with high energy electrons (300 keV results in a significant and irreversible deterioration of their electrical, optical and structural properties. Semiconductors are typically irradiated by low voltage electron accelerators with a continuous flow, the current density in such accelerators is 10–5—10–6 A/cm2, the energy — 0,3—1 MeV. All changes in the properties after such irradiation are resistant at room temperature, and marked properties recovery to baseline values is observed only after prolonged heating of the crystals to a high temperature. In contrast, the authors in their studies observe an improvement of the structural properties of semiconductor crystals (annealing of defects under irradiation with powerful (high current pulsed electron beams of high energy (E0 = 0,3–1 MeV, t = 0,1—10 ns, Ω = 1—10 Hz, j = 20—300 A/cm2. In their previous paper, the authors presented theoretical basis of this effect. This article describes an experimental study on the influence of high-current pulsed electron beams on the optical homogeneity of semiconductor GaAs and CdS crystals, confirming the theory put forward earlier.

  4. Features of Ion-Electronic Emission from Surface of Semiconductors

    Directory of Open Access Journals (Sweden)

    A. Kurochka


    Full Text Available The results of the research value of the current of the secondary electrons in the ion-beam etching of various semiconductors. Shows the setup and electrical circuit of the experiment. An experimental study to determine the dependence of the current of the secondary electrons from the band gap Eg and the height of the potential barrier (electron affinity eχ. It is shown that in the conditions of ion-beam etching of the semiconductor is the penetration of the electric field, which leads to a shift of the energy levels of electrons in the surface layer. Found that the ion-electronic signal emission silicon n-type is higher than the p-type silicon.

  5. Method and system for homogenizing diode laser pump arrays

    Energy Technology Data Exchange (ETDEWEB)

    Bayramian, Andrew James


    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%.

  6. Photon properties of light in semiconductor microcavities

    Institute of Scientific and Technical Information of China (English)

    Guangcun SHAN; Wei HUANG


    Properties of atom-like emitters in cavities are successfully described by cavity quantum electrodynamics(cavity-QED).In this work,we focus on the issue of the steady-state and spectral properties of the light emitted by a driven microcavity containing a quantum well (QW) with the excitonic interactions using simulation of fully quantum-mechanical treatment.The system is coherently pumped with laser,and it is found that depending on the relative values of pumping rate of stimulated emission,either one or two peaks close to the excitation energy of the QW or to the natural frequency of the cavity are shown in the emission spectrum.Furthermore,the nonclassical proprieties of the emitted photon have been investigated.This excitonic system presents several dynamical and statistical similarities to the atomic system,in particular for the bad-cavity and good-cavity limits.The results show that the photon emission can be significantly amplified due to the coupling strength between a single emitter and radiation field in the microcavity,and it is concluded that the present semiconductor microcavity system may serve as a QW laser with low threshold.

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

    CERN Document Server

    Zhao, Zhuang; Nafa, Malik; Chénais, Sébastien; Forget, Sébastien


    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.

  8. High brightness diode-pumped organic solid-state laser (United States)

    Zhao, Zhuang; Mhibik, Oussama; Nafa, Malik; Chénais, Sébastien; Forget, Sébastien


    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.

  9. Fiber-optic parametric amplifier and oscillator based on intracavity parametric pump technique. (United States)

    Luo, Zhengqian; Zhong, Wen-De; Tang, Ming; Cai, Zhiping; Ye, Chenchun; Xiao, Xiaosheng


    A cost-effective fiber optical parametric amplifier (FOPA) based on the laser intracavity pump technique has been proposed and demonstrated experimentally. The parametric process is realized by inserting a 1 km highly nonlinear dispersion-shifted fiber (HNL-DSF) into a fiber ring-laser cavity that consists of a high-power erbium-doped fiber (EDF) amplifier and two highly reflective fiber Bragg gratings. Compared with the conventional parametric pump schemes, the proposed pumping technique is free from a tunable semiconductor laser as the pump source and also the pump phase modulation. When the oscillating power of 530 mW in the EDF laser cavity is achieved to pump the HNL-DSF, a peak parametric gain of 27.5 dB and a net gain over 45 nm are obtained. Moreover, a widely tunable fiber-optic parametric oscillator is further developed using the FOPA as a gain medium.

  10. Modeling of Self-Pumped Singly Resonant Optical Parametric Oscillator

    CERN Document Server

    Deng, Chengxian


    A model of the steady-state operating, self-pumped singly resonant optical parametric oscillator (SPSRO) has been developed. The characteristics of quasi three-level laser gain medium pumped longitudinally have been taken into account. The characteristics of standing wave cavity, reabsorption losses, focusing Gaussian beams of the pump laser, fundamental laser and signal wave have been considered in the analyses. Furthermore, The power characteristics of threshold and efficiency have been analyzed, employing a Yb3+-doped periodically poled lithium niobate co-doped with MgO (Yb3+:MgO:PPLN) as the medium of laser gain and second-order nonlinear crystal.

  11. Large phase shift of spatial soliton in lead glass by cross-phase modulation in pump-signal geometry

    CERN Document Server

    Shou, Qian; Zhang, Xiang; Hu, Wei; Guo, Qi


    We investigate the large phase shifts of the bi-color spatial soliton pair in a cylindrical lead glass rod. The theoretical study suggests a synchronous propagation of a strong pump beam and a weak signal beam under the required initial condition. We experimentally obtain a $\\pi$ phase shift of the signal beam by changing the power of the pump beam by about 14 mW around the soliton critical power, which agrees qualitatively with our theoretical result. The ratio of the phase shift rate of the signal soliton to that of the pump soliton shows a close match to the theoretical estimation.

  12. Comparison of Nd:YAG Ceramic Laser Pumped at 885 nm and 808 nm

    Institute of Scientific and Technical Information of China (English)

    ZONG Nan; ZHANG Xiao-Fu; MA Qing-Lei; WANG Bao-Shan; CUI Da-Fu; PENG Qin-Jun; XU Zu-Yan; PAN Yu-Bai; FENG Xi-Qi


    Laser performance of 1064 nm domestic Nd: YA G ceramic lasers for 885 nm direct pumping and 808 nm traditional pumping are compared. Higher slope efficiency of 34% and maximum output power of 16.5 W are obtained for the 885nm pump with a 6ram length 1 at% Nd:YAG ceramic. The advantages for 885nm direct pumping are discussed in detail. This pumping scheme for highly doping a Nd:YAG ceramic laser is considered as an available way to generate high power and good beam quality simultaneously.

  13. A Shocking New Pump (United States)


    Hydro Dynamics, Inc. received a technical helping hand from NASA that made their Hydrosonic Pump (HPump) a reality. Marshall engineers resolved a bearing problem in the rotor of the pump and recommended new bearings, housings and mounting hardware as a solution. The resulting HPump is able to heat liquids with greater energy efficiency using shock waves to generate heat.

  14. Water Treatment Technology - Pumps. (United States)

    Ross-Harrington, Melinda; Kincaid, G. David

    One of twelve water treatment technology units, this student manual on pumps provides instructional materials for three competencies. (The twelve units are designed for a continuing education training course for public water supply operators.) The competencies focus on the following areas: types of pumps in plant and distribution systems, pump…

  15. Structuring of silicon with low energy focused ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Nebiker, P.W.; Doebeli, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Muehle, R. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)


    The defect production in silicon induced by focused ion beam irradiation as a function of energy and projectile mass has been investigated and compared to the measured sputter yield. The aim was to find optimal beam parameters for the structuring of semiconductors with a minimum amount of defects produced per removed atom. (author) 2 figs., 2 refs.

  16. Basic properties of semiconductors

    CERN Document Server

    Landsberg, PT


    Since Volume 1 was published in 1982, the centres of interest in the basic physics of semiconductors have shifted. Volume 1 was called Band Theory and Transport Properties in the first edition, but the subject has broadened to such an extent that Basic Properties is now a more suitable title. Seven chapters have been rewritten by the original authors. However, twelve chapters are essentially new, with the bulk of this work being devoted to important current topics which give this volume an almost encyclopaedic form. The first three chapters discuss various aspects of modern band theory and the

  17. Electrowetting on semiconductors (United States)

    Palma, Cesar; Deegan, Robert


    Applying a voltage difference between a conductor and a sessile droplet sitting on a thin dielectric film separating it from the conductor will cause the drop to spread. When the conductor is a good metal, the change of the drop's contact angle due to the voltage is given by the Young-Lippmann (YL) equation. Here, we report experiments with lightly doped, single crystal silicon as the conductive electrode. We derive a modified YL equation that includes effects due to the semiconductor and contact line pinning. We show that light induces a non-reversible wetting transition, and that our model agrees well with our experimental results.

  18. Band structure of semiconductors

    CERN Document Server

    Tsidilkovski, I M


    Band Structure of Semiconductors provides a review of the theoretical and experimental methods of investigating band structure and an analysis of the results of the developments in this field. The book presents the problems, methods, and applications in the study of band structure. Topics on the computational methods of band structure; band structures of important semiconducting materials; behavior of an electron in a perturbed periodic field; effective masses and g-factors for the most commonly encountered band structures; and the treatment of cyclotron resonance, Shubnikov-de Haas oscillatio

  19. Semiconductor microcavity polaritons

    Energy Technology Data Exchange (ETDEWEB)

    Vinogradov, Evgenii A [Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow region (Russian Federation)


    The optical properties of wide-gap semiconductor films on metal substrates were investigated experimentally by infrared spectroscopy, Raman scattering, and femtosecond spectroscopy techniques as well as theoretically in the framework of linear crystal optics. The optical spectra of such planar structures (microresonators) were shown to bear information on electromagnetic excitations of both the surface and the volume of the structure. The optical spectra are determined by the interaction of all dipole-active excitations of the component materials with the electromagnetic modes of the microresonator, which in turn are determined by the permittivities of each component material, microcavity (microresonator) thickness, and the experimental conditions. (reviews of topical problems)

  20. Physics of Organic Semiconductors

    CERN Document Server

    Brütting, Wolfgang


    Filling the gap in the literature currently available, this book presents an overview of our knowledge of the physics behind organic semiconductor devices. Contributions from 18 international research groups cover various aspects of this field, ranging from the growth of organic layers and crystals, their electronic properties at interfaces, their photophysics and electrical transport properties to the application of these materials in such different devices as organic field-effect transistors, photovoltaic cells and organic light-emitting diodes. From the contents:. * Excitation Dynamics in O

  1. Hydrogen in semiconductors

    CERN Document Server

    Pankove, Jacques I


    Hydrogen plays an important role in silicon technology, having a profound effect on a wide range of properties. Thus, the study of hydrogen in semiconductors has received much attention from an interdisciplinary assortment of researchers. This sixteen-chapter volume provides a comprehensive review of the field, including a discussion of hydrogenation methods, the use of hydrogen to passivate defects, the use of hydrogen to neutralize deep levels, shallow acceptors and shallow donors in silicon, vibrational spectroscopy, and hydrogen-induced defects in silicon. In addition to this detailed cove

  2. Phase mismatched optical parametric generation in semiconductor magnetoplasma (United States)

    Dubey, Swati; Ghosh, S.; Jain, Kamal


    Optical parametric generation involves the interaction of pump, signal, and idler waves satisfying law of conservation of energy. Phase mismatch parameter plays important role for the spatial distribution of the field along the medium. In this paper instead of exactly matching wave vector, a small mismatch is admitted with a degree of phase velocity mismatch between these waves. Hence the medium must possess certain finite coherence length. This wave mixing process is well explained by coupled mode theory and one dimensional hydrodynamic model. Based on this scheme, expressions for threshold pump field and transmitted intensity have been derived. It is observed that the threshold pump intensity and transmitted intensity can be manipulated by varying doping concentration and magnetic field under phase mismatched condition. A compound semiconductor crystal of n-InSb is assumed to be shined at 77 K by a 10.6μm CO2 laser with photon energy well below band gap energy of the crystal, so that only free charge carrier influence the optical properties of the medium for the I.R. parametric generation in a semiconductor plasma medium. Favorable parameters were explored to incite the said process keeping in mind the cost effectiveness and conversion efficiency of the process.

  3. Semiconductor applications of plasma immersion ion implantation technology

    Indian Academy of Sciences (India)

    Mukesh Kumar; Rajkumar; Dinesh Kumar; P J George


    Many semiconductor integrated circuit manufacturing processes require high dose of implantation at very low energies. Conventional beam line ion implantation system suffers from low beam current at low energies, therefore, cannot be used economically for high dose applications. Plasma immersion ion implantation (PIII) is emerging as a potential technique for such implantations. This method offers high dose rate irrespective of implantation energy. In the present study nitrogen ions were implanted using PIII in order to modify the properties of silicon and some refractory metal films. Oxidation behaviour of silicon was observed for different implantation doses. Diffusion barrier properties of refractory barrier metals were studied for copper metallization.

  4. Fibre-coupled red diode-pumped Alexandrite TEM00 laser with single and double-pass end-pumping (United States)

    Arbabzadah, E. A.; Damzen, M. J.


    We report the investigation of an Alexandrite laser end-pumped by a fibre-coupled red diode laser module. Power, efficiency, spatial, spectral, and wavelength tuning performance are studied as a function of pump and laser cavity parameters. It is the first demonstration, to our knowledge, of greater than 1 W power and also highest laser slope efficiency (44.2%) in a diode-pumped Alexandrite laser with diffraction-limited TEM00 mode operation. Spatial quality was excellent with beam propagation parameter M 2 ~ 1.05. Wavelength tuning from 737-796 nm was demonstrated using an intracavity birefringent tuning filter. Using a novel double pass end-pumping scheme to get efficient absorption of both polarisation states of the scrambled fibre-delivered diode pump, a total output coupled power of 1.66 W is produced in TEM00 mode with 40% slope efficiency.

  5. Transparent Oxide Semiconductors for Emerging Electronics

    KAUST Repository

    Caraveo-Frescas, Jesus Alfonso


    Transparent oxide electronics have emerged as promising materials to shape the future of electronics. While several n-type oxides have been already studied and demonstrated feasibility to be used as active materials in thin film transistors, high performance p-type oxides have remained elusive. This dissertation is devoted to the study of transparent p-type oxide semiconductor tin monoxide and its use in the fabrication of field effect devices. A complete study on the deposition of tin monoxide thin films by direct current reactive magnetron sputtering is performed. Carrier density, carrier mobility and conductivity are studied over a set of deposition conditions where p-type conduction is observed. Density functional theory simulations are performed in order to elucidate the effect of native defects on carrier mobility. The findings on the electrical properties of SnO thin films are then translated to the fabrication of thin films transistors. The low processing temperature of tin monoxide thin films below 200 oC is shown advantageous for the fabrication of fully transparent and flexible thin film transistors. After careful device engineering, including post deposition annealing temperature, gate dielectric material, semiconductor thickness and source and drain electrodes material, thin film transistors with record device performance are demonstrated, achieving a field effect mobility >6.7 cm2V-1s-1. Device performance is further improved to reach a field effect mobility of 10.8 cm2V-1s-1 in SnO nanowire field effect transistors fabricated from the sputtered SnO thin films and patterned by electron beam lithography. Downscaling device dimension to nano scale is shown beneficial for SnO field effect devices not only by achieving a higher hole mobility but enhancing the overall device performance including better threshold voltage, subthreshold swing and lower number of interfacial defects. Use of p-type semiconductors in nonvolatile memory applications is then

  6. Review of magnetohydrodynamic pump applications

    National Research Council Canada - National Science Library

    Al-Habahbeh, O.M; Al-Saqqa, M; Safi, M; Abo Khater, T


    Magneto-hydrodynamic (MHD) principle is an important interdisciplinary field. One of the most important applications of this effect is pumping of materials that are hard to pump using conventional pumps...

  7. Semiconductor devices incorporating multilayer interference regions (United States)

    Biefeld, Robert M.; Drummond, Timothy J.; Gourley, Paul L.; Zipperian, Thomas E.


    A semiconductor high reflector comprising a number of thin alternating layers of semiconductor materials is electrically tunable and may be used as a temperature insensitive semiconductor laser in a Fabry-Perot configuration.

  8. Hydrogen molecules in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Joerg [Technische Universitaet Dresden, 01062 Dresden (Germany)], E-mail:; Hiller, Martin; Lavrov, Edward V. [Technische Universitaet Dresden, 01062 Dresden (Germany)


    Molecular hydrogen, the simplest of all molecules, allows a direct insight into the fundamental properties of quantum mechanics. In the case of H{sub 2}, the Pauli principle leads to two different species, para-H{sub 2} and ortho-H{sub 2}. A conversion between these species is prohibited. Vibrational mode spectra reflect the fundamental properties and allow an unambiguous identification of the H{sub 2} molecules. Today, we have experimental evidence for the trapping of hydrogen molecules in the semiconductors Si, Ge and GaAs at the interstitial sites, within hydrogen-induced platelets, in voids and at impurities (interstitial oxygen in Si). Interstitial H{sub 2} is a nearly free rotor with a surprisingly simple behavior. We review on interstitial H{sub 2} in semiconductors and report on the unexpected preferential disappearance of the para-H{sub 2} or ortho-D{sub 2} species. The origin of the detected ortho-para conversion will be discussed.

  9. Doped semiconductor nanocrystal junctions

    Energy Technology Data Exchange (ETDEWEB)

    Borowik, Ł.; Mélin, T., E-mail: [Institut d’Electronique, de Microélectronique et de Nanotechnologie, CNRS-UMR8520, Avenue Poincaré, F-59652 Villeneuve d’Ascq (France); Nguyen-Tran, T.; Roca i Cabarrocas, P. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS-UMR7647, Ecole Polytechnique, F-91128 Palaiseau (France)


    Semiconductor junctions are the basis of electronic and photovoltaic devices. Here, we investigate junctions formed from highly doped (N{sub D}≈10{sup 20}−10{sup 21}cm{sup −3}) silicon nanocrystals (NCs) in the 2–50 nm size range, using Kelvin probe force microscopy experiments with single charge sensitivity. We show that the charge transfer from doped NCs towards a two-dimensional layer experimentally follows a simple phenomenological law, corresponding to formation of an interface dipole linearly increasing with the NC diameter. This feature leads to analytically predictable junction properties down to quantum size regimes: NC depletion width independent of the NC size and varying as N{sub D}{sup −1/3}, and depleted charge linearly increasing with the NC diameter and varying as N{sub D}{sup 1/3}. We thus establish a “nanocrystal counterpart” of conventional semiconductor planar junctions, here however valid in regimes of strong electrostatic and quantum confinements.

  10. Gating a ferromagnetic semiconductor (United States)

    Bove, A.; Altomare, F.; Kundtz, N.; Chang, A. M.; Cho, Y. J.; Liu, X.; Furdyna, J.


    Ferromagnetic semiconductors have the potential of revolutionizing the way current electronic devices work: more so, because they are compatible with current fabrication lines and can easily be integrated with today's technology. Particular interest lies in III-V Diluted Magnetic Semiconductor (DMS), where the ferromagnetism is hole-mediated and the Curie temperature can therefore be tuned by changing the concentration of free carriers. In these systems, most of the effort is currently applied toward the fabrication of devices working at room-temperature: this implies high carrier density accompanied by low mobility and short mean free path. We will report our results for a ferromagnetic 2DHG system with low carrier density (˜3.4E12 cm-2) and mobility (˜ 1000 cm^2/(Vs)), and we will discuss the effects of local gating in light of possible applications to the fabrication of ferromagnetic quantum dots. T. Dietl et al., Phys. Rev. B 63, 195205 (2001). H. Ohno et al., Nature 408, 944 (2000)

  11. Optical probing of spin-dependent interactions in II-VI semiconductor structures

    Energy Technology Data Exchange (ETDEWEB)

    Gaj, J.A.; Golnik, A.; Goryca, M.; Kossacki, P.; Kowalik, K.; Kudelski, A.; Maslana, W.; Nawrocki, M.; Pacuski, W.; Plochocka, P.; Senellart, P. [Institute of Experimental Physics, Warsaw University, Hoza 69, 00-681 Warszawa (Poland); Cibert, J.; Ferrand, D.; Tatarenko, S. [CNRS-CEA-UJF Joint Group ' ' Nanophysique et semiconducteurs' ' , Laboratoire de Spectrometrie Physique, BP 87, 38402 Saint Martin d' Heres Cedex (France); Karczewski, G.; Kossut, J.; Kutrowski, M. [Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, 02-668 Warszawa (Poland); Krebs, O.; Lemaitre, A.; Voisin, P. [Laboratoire de Photonique et Nanostructures, CNRS, Route de Nozay, 91460 Marcoussis (France); Wojtowicz, T.


    We present a selection of optical experiments, providing information on several spin-dependent interactions in II-VI semiconductor structures. Exciton-exciton and exciton-carrier interactions were studied by time-resolved picosecond pump-probe measurements. Several examples of recent studies involving ion-carrier exchange interaction in quantum wells and layers are discussed, concerning the quest for room temperature ferromagnetic semiconductors, spin temperature of Mn ions in (Cd,Mn)Te quantum wells, and spin relaxation in such wells under pulsed magnetic field. Finally, anisotropic electron-hole exchange in semiconductor quantum dots is discussed in the context of efforts to obtain generation of entangled photon pairs in a biexciton-exciton cascade in a semiconductor quantum dot. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Study of the evanescent wave coupled semiconductor quantum dot amplifying fiber

    Institute of Scientific and Technical Information of China (English)

    WANG Ke-xin; WANG Ting-yun; PANG Fu-fei


    Based on the character of semiconductors and the structure of optical fiber coupler,a new amplifying fiber,coupled semiconductor quantum dot amplifying fiber (CSQDAF),has been presented. A simplified model of PbS quantum dot amplifying fiber is built on the energy band structure of semiconductor quantum dots,and a simple expression deduced from the two-level rate equations and light propagation equations is shown in this paper,by which the gain of quantum dot amplifying fiber can be calculated. A gain of approximately 4.5 dB has been measured in this coupled semiconductor quantum dot amplifying fiber at a wavelength of 1310 nm,when the fiber is pumped by a laser operating at a wavelength of 980 nm with power of 30 mW.

  13. Optical coherent control in semiconductors

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Vadim, Lyssenko; Hvam, Jørn Märcher


    of quantum control including the recent applications to semiconductors and nanostructures. We study the influence of inhomogeneous broadening in semiconductors on CC results. Photoluminescence (PL) and the coherent emission in four-wave mixing (FWM) is recorded after resonant excitation with phase...

  14. Variable temperature semiconductor film deposition (United States)

    Li, Xiaonan; Sheldon, Peter


    A method of depositing a semiconductor material on a substrate. The method sequentially comprises (a) providing the semiconductor material in a depositable state such as a vapor for deposition on the substrate; (b) depositing the semiconductor material on the substrate while heating the substrate to a first temperature sufficient to cause the semiconductor material to form a first film layer having a first grain size; (c) continually depositing the semiconductor material on the substrate while cooling the substrate to a second temperature sufficient to cause the semiconductor material to form a second film layer deposited on the first film layer and having a second grain size smaller than the first grain size; and (d) raising the substrate temperature, while either continuing or not continuing to deposit semiconductor material to form a third film layer, to thereby anneal the film layers into a single layer having favorable efficiency characteristics in photovoltaic applications. A preferred semiconductor material is cadmium telluride deposited on a glass/tin oxide substrate already having thereon a film layer of cadmium sulfide.

  15. II-VI semiconductor compounds

    CERN Document Server


    For condensed matter physicists and electronic engineers, this volume deals with aspects of II-VI semiconductor compounds. Areas covered include devices and applications of II-VI compounds; Co-based II-IV semi-magnetic semiconductors; and electronic structure of strained II-VI superlattices.

  16. Semiconductor photocatalysis principles and applications

    CERN Document Server

    Kisch, Horst


    Focusing on the basic principles of semiconductor photocatalysis, this book also gives a brief introduction to photochemistry, photoelectrochemistry, and homogeneous photocatalysis. In addition, the author - one of the leading authorities in the field - presents important environmental and practical aspects. A valuable, one-stop source for all chemists, material scientists, and physicists working in this area, as well as novice researchers entering semiconductor photocatalysis.

  17. Semiconductor nanostructures in biological applications

    Energy Technology Data Exchange (ETDEWEB)

    Alexson, Dimitri [Department of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Chen Hongfeng [Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Cho, Michael [Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Department of Physics, University of Illinois at Chicago, Chicago, IL 60607 (United States); Dutta, Mitra [Department of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Department of Physics, University of Illinois at Chicago, Chicago, IL 60607 (United States); Li Yang [Department of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Shi, Peng [Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Raichura, Amit [Department of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Ramadurai, Dinakar [Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Parikh, Shaunak [Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Stroscio, Michael A [Department of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Department of Physics, University of Illinois at Chicago, Chicago, IL 60607 (United States); Vasudev, Milana [Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607 (United States)


    Semiconductor nanostructures in biological applications are discussed. Results are presented on the use of colloidal semiconductor quantum dots both as biological tags and as structures that interact with and influence biomolecules. Results are presented on the use of semiconducting carbon nanotubes in biological applications. (topical review)

  18. Pumping machinery theory and practice

    CERN Document Server

    Badr, Hassan M


    Pumping Machinery Theory and Practice comprehensively covers the theoretical foundation and applications of pumping machinery. Key features: Covers characteristics of centrifugal pumps, axial flow pumps and displacement pumpsConsiders pumping machinery performance and operational-type problemsCovers advanced topics in pumping machinery including multiphase flow principles, and two and three-phase flow pumping systemsCovers different methods of flow rate control and relevance to machine efficiency and energy consumptionCovers different methods of flow rate control and relevance to machine effi

  19. Beam rotation and shear in a large electron beam diode

    Energy Technology Data Exchange (ETDEWEB)

    Mansfield, C.R.; Oona, H.; Shurter, R.P.


    The time averaged electron beam current distribution of one of the electron guns of the Large Aperture Module (LAM) of the Aurora laser was measured as part of a larger set of experiments designed to study the electron beam transport to and energy deposition in the LAM laser chamber. The LAM laser chamber has a 1-m {times} 1-m aperture and is pumped from two sides along a 2-m length. A 10 ga. stainless steel sheet was placed inside the laser chamber and served multiple purposes. First, it was used to convert high energy electrons into X-rays in order to make radiograms of the electron beam. Second, the sheet was used as a Faraday cup to measure the total beam current. Third, individual Faraday cups were mounted on the plate to sample the time history of the electron beam at various positions. Each of the LAM electron gun diodes produces a beam of 750 kV electrons with a total current of about 500 kA which is relatively uniform over the cathode area of 1 m {times} 2 m. An applied magnetic field of about 1300 Gauss is used to prevent pinch of the beam during beam transport.

  20. Semiconductor light source with electrically tunable emission wavelength

    Energy Technology Data Exchange (ETDEWEB)

    Belenky, Gregory (Port Jefferson, NY); Bruno, John D. (Bowie, MD); Kisin, Mikhail V. (Centereach, NY); Luryi, Serge (Setauket, NY); Shterengas, Leon (Centereach, NY); Suchalkin, Sergey (Centereach, NY); Tober, Richard L. (Elkridge, MD)


    A semiconductor light source comprises a substrate, lower and upper claddings, a waveguide region with imbedded active area, and electrical contacts to provide voltage necessary for the wavelength tuning. The active region includes single or several heterojunction periods sandwiched between charge accumulation layers. Each of the active region periods comprises higher and lower affinity semiconductor layers with type-II band alignment. The charge carrier accumulation in the charge accumulation layers results in electric field build-up and leads to the formation of generally triangular electron and hole potential wells in the higher and lower affinity layers. Nonequillibrium carriers can be created in the active region by means of electrical injection or optical pumping. The ground state energy in the triangular wells and the radiation wavelength can be tuned by changing the voltage drop across the active region.