Author: "W. Baechtold" - Searchworks@Jio Institute Digital Library Search Results

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1. Efficient Effective Permittivity Treatment for the 2D-FDTD Simulation of Photonic Crystals

Author: K. Rauscher, W. Baechtold, M. Z. Shoushtari, Ch. Hafner, Tahmineh Jalali, Daniel Erni, and Ahmad Mohammadi
Subjects: Permittivity, Computational Mathematics, Materials science, Optics, business.industry, Finite-difference time-domain method, Optoelectronics, General Materials Science, General Chemistry, Electrical and Electronic Engineering, Condensed Matter Physics, business, Photonic crystal
Published: 2007
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2. Alternative formulation of carrier transport in spatially-dependent laser rate equations

Author: W. Baechtold, Daniel Erni, and M. Jungo
Subjects: Physics, education.field_of_study, Ambipolar diffusion, Differential equation, Population, Rate equation, Mechanics, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Semiconductor laser theory, Nonlinear system, Laser diode rate equations, Quantum mechanics, Electrical and Electronic Engineering, Diffusion (business), education
Abstract: The level of accuracy of the conventional implementation of carrier transport into the quantum wells in spatially-dependent rate equations appears too high compared to the overall precision of rate equations. The dynamic description of the normalized carrier profile in the barrier region is of little use, since no stimulated interactions with the optical field occur in this region. Furthermore, it is only described by transverse diffusion and effects such as transport through the graded heterostructures formed by the mirror layers are neglected, which makes its accuracy disputable. Finally, this implementation nearly doubles the time required to solve the carrier rate equations. We propose therefore a more consistent model that still considers the dynamic evolution of the carrier population while assuming a time-invariant profile at the interface between the barrier and the quantum wells. This simplification both removes the requirement for unavailable parameters (such as the ambipolar diffusion coefficient in the barrier) and improves the numerical efficiency of the algorithm since only one additional ordinary differential equation needs be solved. The model is still capable of reproducing the influence of longitudinal transport on the modal distribution and high-frequency behavior of diode lasers.
Published: 2004
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3. Verilog-A implementation of a 2D spatiotemporal VCSEL model for system-oriented simulations of optical links

Author: W. Baechtold, M. Jungo, T. Christen, S. Odermatt, and Daniel Erni
Subjects: Coupling, Multi-mode optical fiber, Computer science, Optical link, Condensed Matter Physics, Laser, Signal, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, law.invention, Vertical-cavity surface-emitting laser, law, Verilog-A, Electronic engineering, Electrical and Electronic Engineering, Cadence
Abstract: An implementation of a highly efficient spatiotemporal vertical-cavity surface-emitting laser (VCSEL) model in the circuit simulation environment of Cadence is presented. The VCSEL model, based on a set of modified rate equations, is written in Verilog-A. It enables the association of the VCSEL model with transistor-level models of the driver and detector circuits. Furthermore, the spatiotemporal nature of the model allows the generation of multimode responses and corresponding far-field intensity profiles, which can be used to investigate fibre coupling and propagation mechanisms. An optimization of the VCSEL drive signal performed using the built-in optimizer of Cadence is presented. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 304–308, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11044
Published: 2003
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4. Quasi-analytic steady-state solution of VCSEL rate equations including spatial hole burning and carrier diffusion losses

Author: Daniel Erni, W. Baechtold, and M. Jungo
Subjects: Physics, Steady state, business.industry, Physics::Optics, Rate equation, Mechanics, Laser, Computer Science Applications, law.invention, Vertical-cavity surface-emitting laser, Optics, Laser diode rate equations, law, Modeling and Simulation, Diffusion current, Electrical and Electronic Engineering, Current (fluid), Diffusion (business), business
Abstract: SUMMARY We propose a new set of equations describing a cylindrical vertical cavity surface emitting laser (VCSEL) cavity under CW operation, based on the rate equations including lateral carrier diffusion. The only numerical step in the calculation consists in finding the roots of a polynomial expression. This model enables a quasi-instantaneous calculation of the laser’s light-current characteristic, including such effects as spatial hole burning, current spreading, inhomogeneous optical intensity distribution, and diffusion losses. An analysis of the VCSELs threshold current and differential quantum efficiency is proposed, which illustrates the interplay between injected current profile and diffusion coefficient. Copyright # 2003 John Wiley & Sons, Ltd.
Published: 2003
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5. Scaling effects on vertical-cavity surface-emitting lasers static and dynamic behavior

Author: M. Jungo, W. Baechtold, Daniel Erni, and Fabrice Monti di Sopra
Subjects: Materials science, business.industry, Relative intensity noise, Oscillation, General Physics and Astronomy, Gain compression, Distributed Bragg reflector, Noise (electronics), Semiconductor laser theory, Laser linewidth, Optics, Optoelectronics, Spontaneous emission, business
Abstract: We investigate the influence of oxide aperture size and number of top distributed Bragg reflector pairs on the performance of oxide confined vertical-cavity surface emitting lasers. Several counteracting mechanisms are shown to result in nonmonotonic behavior, which limits the performance of very small cavities. Static, dynamic, and noise behavior are considered. We examine static operation by means of steady-state measurements, whereas dynamic behavior and noise performance are described by the intrinsic relaxation oscillation frequency, damping coefficient, and Schawlow–Townes linewidth. These parameters are extracted from relative intensity noise measurements. Reducing the oxide aperture up to a given optimal diameter is shown to improve the device’s characteristics. We attribute the performance degradation below this value to increased diffraction losses, reduced confinement factor, and enhanced spontaneous emission. Similarly, increasing the number of Bragg reflector pairs first yields better overall performance as a consequence of reduced mirror losses. However, beyond an optimal value, significant reduction of the differential gain is observed that is attributed to gain compression and possibly thermal effects, degrading both the steady-state and high-frequency performance of the device.
Published: 2002
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6. Novel design topology for ultra low power down converters with broadband on chip matching network

Author: W. Baumberger, U. Lott, W. Baechtold, and M.L. Schmatz
Subjects: Physics, Radiation, Digital down converter, Impedance matching, Topology (electrical circuits), Converters, Condensed Matter Physics, Noise figure, Topology, law.invention, Parasitic capacitance, law, Electrical and Electronic Engineering, Resistor, Electrical impedance
Abstract: A novel design topology for ultra low power receivers and down converters has been developed. Using this topology, a monolithic L-band down converter consisting of an input amplifier and a double balanced mixer has been implemented with a standard 0.7 /spl mu/m GaAs-MESFET process. The circuit has a single ended 50 /spl Omega/ input and differential outputs offering totally more than 40 dB voltage conversion gain at 1 GHz and 30 dB at 2 GHz. It is supplied by a single lithium cell and has a dc power consumption of less than 2.0 mW at 2.7 V. Through a more exact modeling of the parasitic capacitance of n-implanted resistors an improved agreement between measurement and simulation was achieved. Finally, the determination of the noise figure at a high impedance output from a 50 /spl Omega/ measurement is presented.
Published: 1995
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7. 2-D VCSEL model for investigation of dynamic fiber coupling and spatially filtered noise

Author: W. Baechtold, Daniel Erni, and M. Jungo
Subjects: Physics, business.industry, Relative intensity noise, Rate equation, Noise (electronics), Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, law.invention, Vertical-cavity surface-emitting laser, Semiconductor laser theory, Optics, Orders of magnitude (time), Mode partition noise, law, Optical cavity, Electrical and Electronic Engineering, business
Abstract: We propose a set of transformed two-dimensional (2-D) rate equations, which allow the computation of dynamic gain competition resulting from inhomogeneous field and carrier spatial distributions inside a vertical cavity surface-emitting laser cavity. Any explicit spatial dependency has been removed from the modified equations, reducing the computational time by several orders of magnitude. Resulting 2-D dynamic intensity profiles allow investigating effects related to improper fiber coupling due to transverse misalignment between laser beam and fiber. Although the expected increased relative intensity noise (RIN) levels associated with mode partition noise are observed, other effects might have larger contributions to the total noise under specific conditions. We show that the minimum RIN level is not necessarily reached for zero misalignment, but at positions where modes with broad far-field profiles and low power experience important filtering.
Published: 2003
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8. Detection of OH+ and H2O+ towards Orion KL

Author: Maryvonne Gerin, G. A. Blake, J. Stutzki, Shanshan Yu, S. Wang, Paul Hartogh, D. Johnstone, Thomas F. Giesen, Goutam Chattopadhyay, M. Perault, José Cernicharo, Ryszard Szczerba, Rudolf Schieder, Fabien Daniel, S. D. Lord, Jonas Zmuidzinas, Rafael Bachiller, Nathan R. Crockett, Alexandre Karpov, Neal R. Erickson, William B. Latter, John Gill, N. Harada, C. Joblin, P. Zaal, Marie-Lise Dubernet, Erich Schlecht, David A. Neufeld, P. F. Goldsmith, J. A. Murphy, René Liseau, Eric Herbst, C. Comito, Neil Trappe, H. Gupta, E. A. Bergin, A. C. A. Boogert, D. C. Lis, J. R. Goicoechea, Michael Olberg, Jacob Kooi, Jean-Michel Krieg, Frank Maiwald, W. Baechtold, Laurent Pagani, H. W. Yorke, T. A. Bell, F. F. S. van der Tak, Peter Schilke, Martin Emprechtinger, Cecilia Ceccarelli, Volker Ossenkopf, Stephan Schlemmer, Bengt Larsson, Paul B. Rimmer, W. D. Langer, P. J. Encrenaz, R. H. Lin, S.-L. Qin, N. Honingh, J. C. Pearson, Pierrick Martin, M. Salez, S. Cabrit, Emmanuel Caux, Thomas G. Phillips, Karl M. Menten, Sébastien Maret, Rene Plume, Patrick W. Morris, M. C. Diez-Gonzalez, Jesús Martín-Pintado, L. Nordh, Lorene Samoska, R. Güsten, Holger S. P. Müller, Charlotte Vastel, E. Falgarone, Gary J. Melnick, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Ohio State university Departement of Physic, Colombus, Ohio State University [Columbus] (OSU), Ohio State university Departement of Astronomy, Colombus, Ohio State university Departement of Chemistry, Colombus, foreign laboratories (FL), CERN [Genève], Ohio State Univ, Dept Phys, Columbus, OH 43210 USA, Ohio State Univ, Dept Astron & Chem, Columbus, OH 43210 USA, Ohio State University Dept Chemistry, Department of Astronomy [Ann Arbor], University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University-Smithsonian Institution, Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Millimeter-Wave Electronics Laboratory [ETH Zürich] (MWE), Department of Information Technology and Electrical Engineering [Zürich] (D-ITET), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Laboratoire Optimisation de la Conception et Ingénierie de l'Environnement (LOCIE), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), CNRS INSU, UMR 5187, F-31028 Toulouse 4, France, UMR 5187 Toulouse, Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Max Planck Institute for Radio Astronomy, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL), Laboratoire de Radioastronomie (LRA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - 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CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), SRON Netherlands Institute for Space Research (SRON), Department of Physics and Astronomy [Calgary], University of Calgary, I. Physikalisches Institut [Köln], Universität zu Köln = University of Cologne, Laboratoire de Didactique André Revuz (LDAR (EA_4434)), Université d'Artois (UA)-Université Paris Diderot - Paris 7 (UPD7)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12), Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, A.M.Obukhov Institute of Atmospheric Physics (IAP), Russian Academy of Sciences [Moscow] (RAS), Harvard University [Cambridge]-Smithsonian Institution, Univ Toulouse UPS, Ctr Etud Spatiale Rayonnements, F-31062 Toulouse 9, France, Centre Etud Spatiale Rayonnements Toulouse, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), CALTECH, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA, CALTECH, Ctr Infrared Proc & Anal, Pasadena, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Universität zu Köln, Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Université Paris Diderot - Paris 7 (UPD7)-Université d'Artois (UA), Max-Planck-Institut für Sonnensystemforschung (MPS), Department of Physics [Columbus], Department of Astronomy [Columbus], Department chemistry and Biochemistry [Columbus], Department of Physics and Astronomy [Baltimore], Johns Hopkins University (JHU), Smithsonian Institution-Harvard University [Cambridge], Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Observatorio de Yebes, Instituto Geografico Nacional (IGN), Laboratoire de Physique Moleculaire pour l'Atmosphere et l'Astrophysique (LPMAA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich)-Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Ctr Astrobiol CSIC INTA, Lab Astrofis Mol, Madrid 28850, Spain, Ctr Astrobiol CSIC INTA, Lab Astrofis Mol, Madrid, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction de l'Energie Nucléaire (CEA-DEN), Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany, Univ Cologne, Inst Phys 1, and Astronomy
Subjects: [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], HERSCHEL OBSERVATIONS, Analytical chemistry, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, LINE, Astrophysics, LASER MAGNETIC-RESONANCE, 7. Clean energy, 01 natural sciences, ISM: abundances, outflows, Ion, STAR-FORMATION, REGION, NEBULA, Ionization, 0103 physical sciences, Absorption (logic), 010306 general physics, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Physics, SPECTROSCOPY, astrochemistry, Astronomy and Astrophysics, INTERSTELLAR H3O+, Astrophysics - Astrophysics of Galaxies, DIFFUSE CLOUDS, molecular processes, [PHYS.ASTR.GA]Physics [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], 13. Climate action, Space and Planetary Science, COMET-KOHOUTEK, Astrophysics of Galaxies (astro-ph.GA), stars: winds, submillimeter: ISM, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Order of magnitude, line: identification
Abstract: We report observations of the reactive molecular ions OH$^+$, H$_2$O$^+$, and H$_3$O$^+$ towards Orion KL with Herschel/HIFI. All three $N=1-0$ fine-structure transitions of OH$^+$ at 909, 971, and 1033GHz and both fine-structure components of the doublet {\it ortho}-H$_2$O$^+$ $1_{11}-0_{00}$ transition at 1115 and 1139GHz were detected; an upper limit was obtained for H$_3$O$^+$. OH$^+$ and H$_2$O$^+$ are observed purely in absorption, showing a narrow component at the source velocity of 9 kms$^{-1}$, and a broad blueshifted absorption similar to that reported recently for HF and {\it para}-H$_{2}^{18}$O, and attributed to the low velocity outflow of Orion KL. We estimate column densities of OH$^+$ and H$_2$O$^+$ for the 9 km s$^{-1}$ component of $9 \pm 3 \times 10^{12}$cm$^{-2}$ and $7 \pm 2 \times 10^{12}$cm$^{-2}$, and those in the outflow of $1.9 \pm 0.7 \times 10^{13}$cm$^{-2}$ and $1.0 \pm 0.3 \times 10^{13}$cm$^{-2}$. Upper limits of $2.4\times 10^{12}$cm$^{-2}$ and $8.7\times 10^{12}$cm$^{-2}$ were derived for the column densities of {\it ortho} and {\it para}-H$_3$O$^+$ from transitions near 985 and 1657GHz. The column densities of the three ions are up to an order of magnitude lower than those obtained from recent observations of W31C and W49N. The comparatively low column densities may be explained by a higher gas density despite the assumption of a very high ionization rate., 5 pages, 1 figure. Accepted to and to be published in the Herschel HIFI special issue of A\&A Letters
Published: 2010
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9. The Herschel-Heterodyne Instrument for the Far-Infrared (HIFI)

Author: Brian Jackson, B. Kopf, R. Bieber, R. Güsten, A. M. di Giorgio, J. A. Stern, Holger S. P. Müller, B. J. van Leeuwen, G. S. Liu, R. Orfei, Neal R. Erickson, R. Lai, B. Delforges, Wolfgang Wild, Christian Leinz, O. Coeur-Joly, J. Desbat, David Teyssier, S. D. Lord, Karl Jacobs, Bruce Bumble, Lorene Samoska, M. Rataj, R. H. Lin, Dominicus Kester, M. Salez, X. Tielens, Alexandre Karpov, Paolo Saraceno, K. Edwards, R. Huisman, A. Megej, K. F. Schuster, Michel Fich, L. Dubbeldam, Serguei Cherednichenko, H. Golstein, Christian Monstein, J. A. Murphy, C. van Baaren, Victor Belitsky, P. Planesas, E. Natale, Michael Olberg, Lorenzo Piazzo, T. Peacock, Martin Eggens, Emmanuel Caux, W. A. Hatch, Neil Trappe, Hubregt J. Visser, Herbert Zirath, Jaap Evers, S. Phillip-May, Alain Maestrini, Hamid Javadi, Jacob Kooi, Th. de Graauw, F. Schmülling, E. C. Honingh, C. McCoey, J. C. Pearson, W. Luinge, I. Lopez-Fernandez, W. M. Laauwen, M. Michalska, Bengt Larsson, S. Wulff, John Gill, René Liseau, Volker Ossenkopf, Colin Borys, B. Kruizenga, Rafael Teipen, C. Kramer, A. Cros, H. Goulooze, P. Cais, W. Nowosielski, Goutam Chattopadhyay, M. Stokroos, Rafael Bachiller, F. Zwart, C. Gal, Piotr Orleanski, J. Kawamura, H. Smit, O. Siebertz, H. Aarts, Francesco Nuzzolo, L. Meinsma, Jonas Zmuidzinas, R. Assendorp, D. A. Beintema, H. van de Stadt, Jesús Martín-Pintado, G. de Lange, Ryszard Szczerba, Erich Schlecht, R. Higgins, Christophe Risacher, Patrick W. Morris, H. Jacobs, Christopher Jarchow, Willem Jellema, Pieter Dieleman, Todd Gaier, B. Franke, J. Stutzki, Imran Mehdi, Th. Klein, Harald Franz Arno Merkel, T. Finn, M. Justen, P.R. Wesselius, M. Ciechanowicz, T. M. Klapwijk, Hans-Joachim Wunsch, C. Comito, P. Zaal, Erik L. Kollberg, C. Diez-Gonzalez, T. den Boggende, John Ward, Jian-Rong Gao, Pasquale Cerulli-Irelli, C. Kasemann, T. Kuhn, Frank Helmich, K. Wildeman, Henry G. LeDuc, L. Ravera, Frank Maiwald, Y. Delorme, D. Moratschke, F. Schlöder, J. M. Krieg, M. Olbrich, A. Marston, Juan Daniel Gallego, P.-P. Kooiman, E. Steinmetz, T. Gunsing, A. Naber, M. Melchior, Geert Keizer, M. Schultz, I. Peron, S. Gauffre, C. K. Wafelbakker, N. Whyborn, M. Krause, T. Tils, Alexander Loose, A. de Jonge, Pieter R. Roelfsema, Rudolf Schieder, M. Caris, S. Glenz, A. Barcia, W. Baechtold, Paul Hartogh, R. Shipman, Adwin Boogert, Arnold O. Benz, Thomas G. Phillips, California Institute of Technology (CALTECH), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre d'étude spatiale des rayonnements (CESR), Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Université Sciences et Technologies - Bordeaux 1, Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology [Gothenburg, Sweden], Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Dept Pathol & Microbiol, Université de Montréal (UdeM)-Faculté de médecine vétérinaire, Leibniz Institute for Crystal Growth, Leibniz Institute, Technische Universität Darmstadt (TU Darmstadt), Instituto de RadioAstronomía Milimétrica (IRAM), Centre National de la Recherche Scientifique (CNRS), Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster (WWU), Institute of Molecular Medicine and Cell Research (ZBMZ), University of Freiburg [Freiburg], Onsala Space Observatory, Chalmers University of Technology [Göteborg], ESO, European Southern Observatory (ESO), Istituto di Fisica dello Spazio Interplanetario (IFSI), Consiglio Nazionale delle Ricerche (CNR), Max Planck Institute for Meteorology (MPI-M), Institut für Chemie und Dynamik der Geosphäre - Troposphäre (ICG-2), Forschungszentrum Jülich GmbH | Centre de recherche de Juliers, Helmholtz-Gemeinschaft = Helmholtz Association-Helmholtz-Gemeinschaft = Helmholtz Association, Herschel Science Center [Madrid], European Space Astronomy Centre (ESAC), European Space Agency (ESA)-European Space Agency (ESA), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (1965 - 2019) (UNS), École normale supérieure - Paris (ENS-PSL), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Technische Universität Darmstadt - Technical University of Darmstadt (TU Darmstadt), Westfälische Wilhelms-Universität Münster = University of Münster (WWU), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), TNO Industrie en Techniek, and Astronomy
Subjects: Experimental Physics, Local oscillator, Observatories, Orbits, general [Submillimeter], 01 natural sciences, 7. Clean energy, spectroscopic [Techniques], law.invention, Far infrared, Spectrographs, law, spectrographs [Instrumentation], 010303 astronomy & astrophysics, instrumentation: spectrographs, Physics, Spectrometers, submillimeter: general, Bolometers, Correlators, methods: observational, infrared: general, Heterodyne, Frequency band, Submillimeter: generals, Instantaneous phase, Radio spectrum, Optics, Mixers (machinery), 0103 physical sciences, Frequency bands, observational [Methods], 010306 general physics, Remote sensing, techniques: spectroscopic, Spectrometer, business.industry, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Bolometer, generals [Submillimeter], Astronomy and Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Launching, general [Infrared], Space and Planetary Science, Heterodyning, Instruments, business
Abstract: International audience; Aims: This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI) that was launched onboard ESA's Herschel Space Observatory in May 2009. Methods: The instrument is a set of 7 heterodyne receivers that are electronically tuneable, covering 480-1250 GHz with SIS mixers and the 1410-1910 GHz range with hot electron bolometer (HEB) mixers. The local oscillator (LO) subsystem comprises a Ka-band synthesizer followed by 14 chains of frequency multipliers and 2 chains for each frequency band. A pair of auto-correlators and a pair of acousto-optical spectrometers process the two IF signals from the dual-polarization, single-pixel front-ends to provide instantaneous frequency coverage of 2 × 4 GHz, with a set of resolutions (125 kHz to 1 MHz) that are better than 0.1 km s-1. Results: After a successful qualification and a pre-launch TB/TV test program, the flight instrument is now in-orbit and completed successfully the commissioning and performance verification phase. The in-orbit performance of the receivers matches the pre-launch sensitivities. We also report on the in-orbit performance of the receivers and some first results of HIFI's operations. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
Published: 2010
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10. Herschel observations of EXtra-Ordinary Sources (HEXOS): detecting spiral arm clouds by CH absorption lines

Author: R. Bachille, T. A. Bell, H. Gupta, A. C. A. Boogert, H. W. Yorke, Martin Emprechtinger, Nathan R. Crockett, Cecilia Ceccarelli, P. J. Encrenaz, M. Perault, José Cernicharo, Laurent Pagani, Volker Ossenkopf, Eric Herbst, R. Rolffs, D. C. Lis, Pierrick Martin, Thomas F. Giesen, Emmanuel Caux, C. Joblin, E. Falgarone, Karl M. Menten, D. Johnstone, S.-L. Qin, T. Möller, Gary J. Melnick, Peter Schilke, J. R. Goicoechea, Michael Olberg, M. Salez, Sébastien Maret, Rene Plume, Jacob Kooi, Stephan Schlemmer, Patrick W. Morris, Jesús Martín-Pintado, Thomas G. Phillips, J. C. Pearson, W. Baechtold, Arnaud Belloche, Goutam Chattopadhyay, S. D. Lord, Alexandre Karpov, N. Honingh, Charlotte Vastel, C. Comito, E. A. Bergin, Neil Trappe, J. L. Gill, J. Stutzki, J.-M. Krieg, Fabien Daniel, L. H. Nordh, Jonas Zmuidzinas, S. Cabrit, M. C. Diez-Gonzalez, Maryvonne Gerin, Rudolf Schieder, F. F. S. van der Tak, Paul Hartogh, W. D. Langer, Marie-Lise Dubernet, S. Wang, G. A. Blake, Shanshan Yu, R. Güsten, Holger S. P. Müller, David A. Neufeld, P. F. Goldsmith, J. A. Murphy, Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), I. Physikalisches Institut [Köln], Universität zu Köln, Max Planck Institute for Radio Astronomy, Hamburger Synchrotronstrahlungslabor HASYLAB at Deutsches Elektronen Synchrotron DESY (HASYLAB), Deutsches Elektronen-Synchrotron [Hamburg] (DESY), Université de Cologne, Institut de Physique 1, Université de Cologne, Max-Planck-Institut für Radioastronomie (MPIFR), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), California Institute of Technology (CALTECH), Department of Astronomy [Ann Arbor], University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Laboratoire Optimisation de la Conception et Ingénierie de l'Environnement (LOCIE), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Univ Toulouse UPS, Ctr Etud Spatiale Rayonnements, F-31062 Toulouse 9, France, Centre Etud Spatiale Rayonnements Toulouse, CNRS INSU, UMR 5187, F-31028 Toulouse 4, France, UMR 5187 Toulouse, Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Université Paris sciences et lettres (PSL), Cahill Center for Astronomy and Astrophysics, Laboratoire de Radioastronomie (LRA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Ohio State Univ, Dept Phys, Columbus, OH 43210 USA, Ohio State University [Columbus] (OSU), Ohio State Univ, Dept Astron & Chem, Columbus, OH 43210 USA, Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V9E 2E7 Canada, Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, Laboratoire de Modélisation Multi-échelles des Combustibles (LM2C), Service d'Etudes de Simulation du Comportement du combustibles (SESC), Département d'Etudes des Combustibles (DEC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Département d'Etudes des Combustibles (DEC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, CALTECH, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA, CALTECH, Ctr Infrared Proc & Anal, Pasadena, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), SRON Netherlands Institute for Space Research (SRON), foreign laboratories (FL), CERN [Genève], Department of Physics and Astronomy [Calgary], University of Calgary, Laboratoire de Didactique André Revuz (LDAR (EA_4434)), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Université Paris Diderot - Paris 7 (UPD7)-Université d'Artois (UA), Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, A.M.Obukhov Institute of Atmospheric Physics (IAP), Russian Academy of Sciences [Moscow] (RAS), Millimeter-Wave Electronics Laboratory [ETH Zürich] (MWE), Department of Information Technology and Electrical Engineering [Zürich] (D-ITET), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Onsala Space Observatory, Chalmers University of Technology [Göteborg], Faure, Alexandre, Universität zu Köln = University of Cologne, École normale supérieure - Paris (ENS-PSL), Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Harvard University-Smithsonian Institution, Infrared Processing and Analysis Center (IPAC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université d'Artois (UA)-Université Paris Diderot - Paris 7 (UPD7)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany, Univ Cologne, Inst Phys 1, École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Ctr Astrobiol CSIC INTA, Lab Astrofis Mol, Madrid 28850, Spain, Ctr Astrobiol CSIC INTA, Lab Astrofis Mol, Madrid, Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), California Institute of Technology (CALTECH)-NASA, CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction de l'Energie Nucléaire (CEA-DEN), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich)-Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), and Astronomy
Subjects: Physics, Spiral galaxy, 010504 meteorology & atmospheric sciences, Absorption spectroscopy, Experimental Physics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Line width, Astrophysics - Astrophysics of Galaxies, Galaxy, ISM: abundances, ISM: molecules, Linear relationship, [PHYS.ASTR.GA]Physics [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Spectral resolution, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: We have observed CH absorption lines ($J=3/2, N=1 \leftarrow J=1/2, N=1$) against the continuum source Sgr~B2(M) using the \textit{Herschel}/HIFI instrument. With the high spectral resolution and wide velocity coverage provided by HIFI, 31 CH absorption features with different radial velocities and line widths are detected and identified. The narrower line width and lower column density clouds show `spiral arm' cloud characteristics, while the absorption component with the broadest line width and highest column density corresponds to the gas from the Sgr~B2 envelope. The observations show that each `spiral arm' harbors multiple velocity components, indicating that the clouds are not uniform and that they have internal structure. This line-of-sight through almost the entire Galaxy offers unique possibilities to study the basic chemistry of simple molecules in diffuse clouds, as a variety of different cloud classes are sampled simultaneously. We find that the linear relationship between CH and H$_2$ column densities found at lower $A_V$ by UV observations does not continue into the range of higher visual extinction. There, the curve flattens, which probably means that CH is depleted in the denser cores of these clouds., Comment: Accepted for publication in A&A, HIFI Special Issue
Published: 2010
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11. Residual-carrier free, balanced optical phase locked loop for inter-satellite communications

Author: K. Kudielka, F. Herzog, W. Baechtold, and Daniel Erni
Subjects: Physics, Phase-locked loop, Optics, business.industry, Optical transistor, Optical cross-connect, Electronic engineering, Optical modulation amplitude, Optical performance monitoring, business, Optical switch, Residual carrier, Optical communications repeater
Abstract: We present a coherent optical commu nication system for inter-satellite links with a new type of Optical Phase Lock Loop (OPLL). The OPLL requires no residual carrier transmission, although it employs a conventional 180° 3 dB hybrid and an AC-coupled balanced front end.
Published: 2006
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12. Fiber dispersion induced nonlinearity in fiber-optic links with multimode laser diodes

Author: W. Baechtold and S. Hunziker
Subjects: Physics, Optical fiber, business.industry, Physics::Optics, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, law.invention, Semiconductor laser theory, Optics, Modulation, law, Dispersion (optics), Modal dispersion, Optoelectronics, Fiber, Electrical and Electronic Engineering, business, Diode, Intermodulation
Abstract: In analog RF fiber-optic (FO) links with directly modulated multimode laser diodes (LD's), nonlinear distortions of the received modulation signal occur due to fiber dispersion. Using a simple analytical two mode model, we show that the mutual compensation of strong nonlinearities between particular modes breaks down at high-modulation frequencies. The effect can be observed even in 1300-nm links with single-mode (SM) standard fibers. Simulations as well as measurements of intermodulation (IM) illustrate this argument.
Published: 1997
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13. A flip-flop and logic gate with Josephson junctions

Author: W. Baechtold
Subjects: Josephson effect, Physics, Pass transistor logic, business.industry, Electrical engineering, Hardware_PERFORMANCEANDRELIABILITY, Emitter-coupled logic, Resistor–transistor logic, law.invention, Pi Josephson junction, law, Logic gate, Hardware_INTEGRATEDCIRCUITS, Hardware_ARITHMETICANDLOGICSTRUCTURES, business, Flip-flop, AND gate, Hardware_LOGICDESIGN
Abstract: A complementary logic circuit with Josephson junctions has been investigated theoretically and experimentally. This paper will discuss a circuit with a measured risetime of 100 ps, a power dissipation of 16.4 μW, with the flip-flop operated with a 1500-MHz input signal.
Published: 2005
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14. Realistic two-dimensional models for planar photonic crystal devices

Author: Daniel Erni, W. Baechtold, Jan-Robert van Look, Patric Strasser, Robert Wueest, K. Rauscher, Rik Harbers, and Franck Robin
Subjects: business.industry, Scattering, Chemistry, Finite-difference time-domain method, Physics::Optics, Tapering, law.invention, Optics, Planar, law, Phenomenological model, Hexagonal lattice, business, Waveguide, Photonic crystal
Abstract: We have studied tapers that couple light from a conventional ridge waveguide into a planar photonic crystal (PhC) waveguide. Tapering is achieved by changing the PhC waveguide width either in steps or gradually. Lag effects in fabrication provide an additional tapering due to the fact that the hole depths scale with the corresponding hole diameter. Our analysis deals with the out-of-plane loss that arises within such taper sections. The PhC consists of a triangular lattice of air holes introduced into an InGaAsP/InP slab structure. For conceptual studies we use the 2D multiple multipole method (MMP) in conjunction with an extended phenomenological model. This model covers the out-of-plane scattering providing a loss parameter and an effective index correction for the holes under consideration. This realistic 2D model is retrieved from full-wave 3D FDTD simulations and measurements.
Published: 2004
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15. Lasing in a 2D photonic bandgap structure

Author: W. Baechtold, Asma Jebali, Ernst B. Kley, Gian-Luca Bona, Christian Bauer, Rainer F. Mahrt, Daniel Erni, and Nikolaj Moll
Subjects: chemistry.chemical_classification, Materials science, business.industry, Physics::Optics, Stopband, Polymer, engineering.material, Grating, Distributed Bragg reflector, Optical pumping, Optics, Coating, chemistry, engineering, Optoelectronics, business, Lasing threshold, Photonic bandgap
Abstract: Organic two-dimensional photonic bandgap structures (2D PBG) have been fabricated by spin-coating a thin polymer film onto a nano-patterned SiO2 circular-grating surface-emitting distributed Bragg reflectors (CG-SE-DBR). When optically pumped and for certain grating parameters, these structures exhibit a peak inside the stop band that leads to lasing with a reduced threshold. An analytical model based on the transfer-matrix method has been developed to investigate the origin of this peak. The theoretical results are in excellent agreement with the experimental findings.
Published: 2004
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16. An active tagging system using circular polarization modulation

Author: W. Baechtold, Marcel Kossel, and H. Benedickter
Subjects: Physics, Microstrip antenna, Computational complexity theory, Modulation, Electronic engineering, Demodulation, ComputerSystemsOrganization_SPECIAL-PURPOSEANDAPPLICATION-BASEDSYSTEMS, Polarization (waves), Microwave, Multipath propagation, Circular polarization
Abstract: An active read/write microwave tagging system using circular polarization modulation as a novel modulation scheme for RFID systems to reduce demodulation complexity and power consumption on the battery powered tag is presented. Additional coding of the circular polarization modulated data reduces transmission errors due to polarization inversion at multipath propagation.
Published: 2003
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17. Circular polarized aperture coupled patch antennas for an RFID system in the 2.4 GHz ISM band

Author: H. Benedickter, W. Baechtold, and M. Kossel
Subjects: Physics, Super high frequency, Reconfigurable antenna, Directional antenna, business.industry, Reflective array antenna, Fresnel zone antenna, Astrophysics::Instrumentation and Methods for Astrophysics, Slot antenna, law.invention, Biconical antenna, Optics, Horn antenna, law, High Energy Physics::Experiment, Physics::Chemical Physics, business, Computer Science::Information Theory
Abstract: The design of aperture coupled patch (ACP) antennas for an RFID system in the 2.4 GHz ISM using circular polarization modulation is presented. Due to the requirements of the modulation scheme the ACP antennas are circularly polarized with switchable polarization sense. Four ACP antennas are compared according to their impedance and gain bandwidth, axial ratio, and crosspolarization isolation. Among the presented antennas a novel compact ACP antenna is shown that allows replacement of the conventional quadrature hybrid polarizer by /spl lambda//4 quarter transmission lines.
Published: 2003
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18. GaAs device activities in Europe

Author: W. Baechtold
Subjects: Computer science, law, business.industry, Electrical engineering, JFET, MESFET, Integrated circuit, business, law.invention, Processing methods
Abstract: This survey of European GaAs device activities focuses on GaAs MESFETs, HEMTs, and GaInAs JFETs. In all areas significant progress is noted and attributed to advanced processing methods. In the case of the GaInAs JFET, outstanding device results are cited. It is felt that the technology, however, is presently suited to very simple integrated circuits only and that of tools and processes similar to those for MESFETs are needed similar levels of integration to become feasible. >
Published: 2003
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19. Determination of the noise source parameters in AlInAs/GaInAs HEMT heterostructures based on measured noise temperature dependence on the electric field

Author: C. Bergamaschi, W. Patrick, and W. Baechtold
Subjects: Noise temperature, Materials science, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Heterojunction, High-electron-mobility transistor, Gallium arsenide, chemistry.chemical_compound, chemistry, Electric field, Equivalent circuit, Optoelectronics, business, Noise (radio)
Abstract: The noise temperature dependence on the electric field in an AlInAs/GaInAs HEMT heterostructure has been measured. It was found that the dependence of the noise temperature on the electric field in GaAs MESFETs and in AlInAs/GaInAs HEMTs are remarkably different. For this reason a different model must be used for AlInAs/GaInAs HEMTs. Based on the measured noise temperature dependence on the electric field, am analytic noise model for the AlInAs/GaInAs HEMT has been developed. The noise source parameters were calculated and compared with extracted noise source parameters from noise measurements. >
Published: 2002
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20. Approach for developing a large signal model of a 150 GHz HEMT

Author: B.-U.H. Klepser, W. Patrick, Christian G. Diskus, M. Schefer, C. Bergamaschi, and W. Baechtold
Subjects: Engineering, business.industry, Transistor, Spice, Hardware_PERFORMANCEANDRELIABILITY, Large-signal model, High-electron-mobility transistor, computer.software_genre, law.invention, Simulation software, Gallium arsenide, chemistry.chemical_compound, chemistry, law, Hardware_INTEGRATEDCIRCUITS, Electronic engineering, Scattering parameters, business, computer, Voltage
Abstract: In this contribution the development of a large signal model describing the electrical behaviour of an InAlAs/InGaAs/InP-HEMT will be discussed. The transistors under question were fabricated at our laboratory. They revealed a transit frequency of 150 GHz, which is, to our knowledge, the best result obtained with a T-gate of 0.25 /spl mu/m footprint. The aim of this project was to develop a model of this transistor for simulating nonlinear circuits with commercial simulator software like HP-MDS or Spice. The procedure results in an easily applicable model which produces very good fits to the measured S-parameters.
Published: 2002
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21. Depletion and enhancement mode InP high electron mobility transistors fabricated by a dry gate recess process

Author: W. Patrick, Rebecca Cheung, and W. Baechtold
Subjects: Materials science, business.industry, Transconductance, Transistor, Electrical engineering, Cutoff frequency, Threshold voltage, law.invention, chemistry.chemical_compound, chemistry, Etching (microfabrication), law, Indium phosphide, Optoelectronics, Dry etching, business, Indium gallium arsenide
Abstract: We report depletion and enhancement mode InP high electron mobility transistors (HEMTs) fabricated using CH/sub 4//H/sub 2/ selective dry etch gate recess process. Under the etching conditions developed, the process has a In/sub 0.7/Ga/sub 0.3/As to In/sub 0.52/Al/sub 0.48/As selectivity of 130. The dc threshold voltages of the devices fabricated in this way increase from -1.3 V to 0.1 V as a function of dry etch time, with an extrinsic transconductance of 520 mS/mm in the depletion mode and 800 mS/mm in enhancement mode. The devices exhibit an extrapolated cut-off frequencies of 150 GHz. This work demonstrates the potential of the use of dry etching as a gate recess technology for the future development of high frequency InP-based circuits.
Published: 2002
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22. Improvements on a GaAs MESFET model for nonlinear RF simulations

Author: Frank Ellinger, J. Kucera, and W. Baechtold
Subjects: Linear region, Materials science, business.industry, Conductance, Charge (physics), Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Capacitance, Gallium arsenide, Nonlinear system, chemistry.chemical_compound, chemistry, Equivalent circuit, Optoelectronics, MESFET, business
Abstract: A modified GaAs MESFET-model has been developed to improve accuracy over a large bias range, particularly within the linear region. The enhancements consist of a modified Statz equation for the gate charge to improve the modeling of the gate drain capacitance, and an equation for the bias dependent drain source resistance for exact modeling of the dispersive output conductance.
Published: 2002
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23. Broadband noise parameter and S-parameter measurement technique

Author: W. Baechtold and M.L. Schmatz
Subjects: Noise temperature, Engineering, Noise generator, Noise measurement, business.industry, Electronic engineering, Effective input noise temperature, Y-factor, Tuner, business, Noise figure, Noise floor
Abstract: An accurate noise parameter measurement technique is presented that uses an amplifier/attenuator noise source, a multi-octave tuner and a directional coupler for noise injection at all tuner states. The presented concept allows measurements with more than 30 different ENR steps and the ability to calibrate the ENR during system calibration. A system that demonstrates the concept was built for the frequency range from 0.5-6.0 GHz.
Published: 2002
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24. Reversal of infall in SgrB2(M) revealed by Herschel/HIFI observations of HCN lines at THz frequencies

Author: P. J. Encrenaz, Sébastien Maret, Edwin A. Bergin, Emmanuel Caux, Shanshan Yu, Thomas G. Phillips, John Gill, Neil Trappe, Javier R. Goicoechea, M. Perault, José Cernicharo, D. Johnstone, Peter Schilke, Stephan Schlemmer, T. A. Bell, Maryvonne Gerin, Volker Ossenkopf, S.-L. Qin, Claudia Comito, P. F. Goldsmith, Martin Emprechtinger, S. D. Lord, H. Gupta, Dariusz C. Lis, Thomas F. Giesen, Rene Plume, Patrick W. Morris, Marie-Lise Dubernet, Charlotte Vastel, Cecilia Ceccarelli, Jesús Martín-Pintado, L. Nordh, Pierrick Martin, J. Stutzki, R. Rolffs, Karl M. Menten, Fabien Daniel, Rolf Guesten, W. D. Latter, Goutam Chattopadhyay, W. Baechtold, Geoffrey A. Blake, C. Joblin, Gary J. Melnick, H. S. P. Mueller, H. W. Yorke, J. A. Murphy, W. D. Langer, Michael Olberg, Nathan R. Crockett, Rafael Bachiller, Eric Herbst, J. C. Pearson, M. C. Diez-Gonzalez, Jonas Zmuidzinas, F. F. S. van der Tak, S. Wang, Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Astronomy, Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Experimental Physics, 010504 meteorology & atmospheric sciences, Opacity, ISM: structure, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, COLOGNE DATABASE, STAR-FORMATION, 0103 physical sciences, Radiative transfer, Astrophysics::Solar and Stellar Astrophysics, Isotopologue, FACILITY, OUTFLOW, Emission spectrum, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Physics, ISM: kinematics and dynamics, CDMS, stars: formation, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Star formation, Molecular cloud, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Accretion (astrophysics), ISM: molecules, [SDU]Sciences of the Universe [physics], 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), MOLECULAR-SPECTROSCOPY, submillimeter: ISM, Vector field, Astrophysics::Earth and Planetary Astrophysics, ISM: individual objects: SgrB2(M), B2, HIFI
Abstract: To investigate the accretion and feedback processes in massive star formation, we analyze the shapes of emission lines from hot molecular cores, whose asymmetries trace infall and expansion motions. The high-mass star forming region SgrB2(M) was observed with Herschel/HIFI (HEXOS key project) in various lines of HCN and its isotopologues, complemented by APEX data. The observations are compared to spherically symmetric, centrally heated models with density power-law gradient and different velocity fields (infall or infall+expansion), using the radiative transfer code RATRAN. The HCN line profiles are asymmetric, with the emission peak shifting from blue to red with increasing J and decreasing line opacity (HCN to H$^{13}$CN). This is most evident in the HCN 12--11 line at 1062 GHz. These line shapes are reproduced by a model whose velocity field changes from infall in the outer part to expansion in the inner part. The qualitative reproduction of the HCN lines suggests that infall dominates in the colder, outer regions, but expansion dominates in the warmer, inner regions. We are thus witnessing the onset of feedback in massive star formation, starting to reverse the infall and finally disrupting the whole molecular cloud. To obtain our result, the THz lines uniquely covered by HIFI were critically important., A&A, HIFI special issue, accepted
Published: 2010
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25. Active compensation of improper waveguide coupling through vertical-cavity surface-emitting laser electronic beam shaping

Author: M. Jungo, W. Baechtold, and Daniel Erni
Subjects: Distributed feedback laser, Materials science, business.industry, Physics::Optics, Statistical and Nonlinear Physics, Beam parameter product, Atomic and Molecular Physics, and Optics, Vertical-cavity surface-emitting laser, Laser linewidth, Optics, Quantum dot laser, Optoelectronics, Laser beam quality, Laser power scaling, business, Tunable laser
Abstract: We propose a new asymmetric drive scheme for vertical-cavity surface-emitting lasers (VCSELs) that is expected to permit the active compensation of misalignment between laser beam and waveguide. Simulations performed with a VCSEL integrated spatiotemporal advanced simulator simulation tool indicate that driving the laser with two orthogonal, individually addressable contacts may improve coupling efficiency by selective excitation of modes with given azimuthal distributions. Besides improved and more-stable coupling efficiency, significantly lower noise levels that result from reduced mode partition noise are observed, which significantly enhance the performance of digital transmission systems. Such electronic beam shaping from the driver side may drastically reduce the system’s costs by relaxing its fabrication tolerances.
Published: 2003
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26. Cellular remote antenna feeding: Optical fibre or coaxial cable?

Author: W. Baechtold and S. Hunziker
Subjects: Engineering, Optical fiber, business.industry, Coaxial cable, Dynamic range, Cellular radio, Cellular telephone, law.invention, law, GSM, Electronic engineering, Electrical and Electronic Engineering, Coaxial, Antenna (radio), business
Abstract: Remote antennas in cellular telephone networks can be supplied by coaxial cable or optical fibre. It is useful to know which of the two technologies is more appropriate with respect to dynamic range and costs. Coaxial and optical fibre links are considered for GSM applications. The link length-dependent costs are compared for two reasonable values of the dynamic range.
Published: 1998
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27. Simple model for fundamental intermodulation analysis of RF amplifiers and links

Author: W. Baechtold and S. Hunziker
Subjects: Third-order intercept point, Engineering, Optical fiber, business.industry, Second-order intercept point, Amplifier, Electrical engineering, law.invention, Simple (abstract algebra), law, Electronic engineering, Point (geometry), Limit (mathematics), Electrical and Electronic Engineering, business, Intermodulation
Abstract: In modern low cost RF amplifiers or fibre optic links, it is essential to know the limit of the third order intercept point definition to make accurate intermodulation predictions. The authors present a simple formula to calculate this limit from the data sheet parameters' third order intercept point and 1dB compression point.
Published: 1996
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28. Determination of the RF-noise source parameters in AlInAs/GaInAs-HEMT heterostructures based on measured noise temperature dependence against electric field

Author: W. Patrick, W. Baechtold, and C. Bergamaschi
Subjects: Noise temperature, Rf noise, business.industry, Chemistry, Astrophysics::Instrumentation and Methods for Astrophysics, Y-factor, Heterojunction, High-electron-mobility transistor, chemistry.chemical_compound, Ternary compound, Electric field, Electronic engineering, Optoelectronics, Electrical and Electronic Engineering, business, Noise (radio)
Abstract: The noise temperature dependence on the electric field in an AlInAs/GaInAs-HEMT heterostructure has been measured. It was found that the dependence of the noise temperature on the electric field in GaAs-MESFETs and in AlInAs/GaInAs-HEMTs is remarkably different. For this reason a different model must be used for AlInAs/GaInAs-HEMTs. Based on the measured noise temperature dependence on the electric field, an analytic noise model for the AlInAs/GaInAs HEMT has been developed. The noise source parameters were calculated and compared with extracted noise source parameters from noise measurements.
Published: 1995
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29. Contributors

Author: G. K. Cambrell, J. B. Davies, H. Toussaint, M. A. Murray-Lasso, R.J.M. Govaerts, P. A. MacDonald, M. K. McPhun, O. P. Gupta, D. H. Sinnott, W. Baechtold, J. R. Molberg, A. B. MacNee, E. B. Kozemchak, D. T. Thomas, J. E. Dalley, I.A. Cermak, P. E. Green, H. E. Green, L. W. Read, A. Vander Vorst, G. H. Cohen, Peter P. Silvester, D. K. Reynolds, P. J. Tu, T. W. Houston, W. N. Parker, Auguste Laloux, D. W. Kammler, A. Wexler, H. J. Carlin, A. E. Smoll, R.M. Bulley, C. T. Carson, A. R. Karnik, J.W. Bandler, S. Mahdi, W. Kotyczka, R. R. Gupta, and M. J. O. Strutt
Subjects: Radiation, Electrical and Electronic Engineering, Condensed Matter Physics
Published: 1969
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30. Computerized Calculation of Small Signal and Noise Properties of Microwave Transistors

Author: W. Kotyczka, M. J. O. Strutt, and W. Baechtold
Subjects: Noise temperature, Engineering, Radiation, business.industry, Acoustics, Y-factor, Hardware_PERFORMANCEANDRELIABILITY, Condensed Matter Physics, Noise figure, Noise (electronics), Burst noise, Noise generator, Hardware_INTEGRATEDCIRCUITS, Electronic engineering, Effective input noise temperature, Flicker noise, Electrical and Electronic Engineering, business
Abstract: The small signal and noise equivalent circuit of a microwave transistor is evaluated using an analog simulation model. The noise figure has been determined with the same model as a function of the source admittance and the frequency. The s parameters and noise figures are compared with the results calculated on a digital computer.
Published: 1969
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31. X- and Ku-band amplifiers with GaAs Schottky-barriers field-effect transistors

Author: W. Baechtold
Subjects: Materials science, business.industry, Amplifier, Transistor, Schottky diode, Transistor array, Noise figure, Ku band, law.invention, law, Optoelectronics, Field-effect transistor, Electrical and Electronic Engineering, business, Monolithic microwave integrated circuit
Abstract: During recent years significant progress has been made in GaAs technology and the GaAs Schottky-barrier field-effect transistor now shows outstanding microwave gain and noise properties. Two experimental microwave amplifiers demonstrate that the device is very well suited for broad-band applications and that large bandwidth in the X- and Ku-band can be obtained with simple circuits. The first of the two three-stage amplifiers realized was optimized with respect to noise and a noise figure of 3.8 dB was obtained at 8 GHz; the maximum gain is 17.5 dB at 8.3 GHz and the 3-dB bandwidth is 1.3 GHz. The second amplifier has a maximum gain of 11.5 dB at 11.5 GHz. The gain is greater than 8.5 dB in the range 9.5-14.3 GHz.
Published: 1973
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32. Noise behavior of GaAs field-effect transistors with short gate lengths

Author: W. Baechtold
Subjects: Noise temperature, Materials science, Noise-figure meter, business.industry, Shot noise, Y-factor, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Electronic, Optical and Magnetic Materials, Burst noise, Noise generator, Optoelectronics, Flicker noise, Electrical and Electronic Engineering, business, Noise (radio)
Abstract: The noise behavior of the GaAs Schottky-barrier gate field-effect transistor has been investigated theoretically and experimentally. It has been found that an additional noise source has to be taken into account in GaAs FET's biased in the pinchoff region: the intervalley scattering noise. This noise source has been investigated and a new transistor noise model is proposed. Measured and calculated noise figures show good agreement in the frequency range 2-10 GHz. It is shown that the influence of the intervalley scattering noise can be reduced by reducing the channel thickness, and that such devices show excellent gain and noise properties in the X band.
Published: 1972
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33. Contributors, September, 1968

Author: C.L. Trembath, E.F. Sherer, J.A. Hall, P.I. Somlo, B.L. Seidel, M.J.O. Strutt, Dan A. Bathker, W.J. Foote, J.A. De Gruyl, J.G. Smith, W.A. Johnson, J. Halford, G.G. Haroules, D.L. Hollway, J.M. Kenney, S. Kanema, G. Levy, K.W. Olson, A.V. McDaniel, T.Y. Otoshi, K. Hirano, W. H. Higa, T. Mukaihata, J.H. Dunn, D.D. Howard, J.-P. Hach, J.G. Ondria, W.E. Brown, W. Baechtold, J.-C.R. Collinet, C. Denson, H.J. Peppiatt, F. M. Palka, C.T. Stelzried, B. Senitzky, T. Nemoto, G.F. Engen, M.E. Hines, D.F. Wait, J.R. Ashley, S. Okwit, A.A. Penzias, W.O. Schlosser, C.B. Searles, and K.H. Sann
Subjects: Radiation, Electrical and Electronic Engineering, Condensed Matter Physics
Published: 1968
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34. Noise behavior of Schottky barrier gate field-effect transistors at microwave frequencies

Author: W. Baechtold
Subjects: Materials science, business.industry, Schottky barrier, Transistor, Metal–semiconductor junction, Electronic, Optical and Magnetic Materials, law.invention, Computer Science::Hardware Architecture, Computer Science::Emerging Technologies, law, Optoelectronics, Equivalent circuit, Flicker noise, Field-effect transistor, Electrical and Electronic Engineering, business, Microwave, Noise (radio)
Abstract: The noise behavior of a Schottky barrier gate field-effect transistor is investigated by the use of the noise equivalent circuit. The influence of the carrier velocity saturation is estimated. The noise parameters are calculated by taking into account the influence of parasitic resistances. Measured and calculated noise parameters show good agreement in the frequency range 2-8 GHz.
Published: 1971
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35. 2-D VCSEL model for investigation of dynamic fiber coupling and spatially filtered noise.

Author: M. Jungo, D. Erni, and W. Baechtold
Abstract: We propose a set of transformed two-dimensional (2-D) rate equations, which allow the computation of dynamic gain competition resulting from inhomogeneous field and carrier spatial distributions inside a vertical cavity surface-emitting laser cavity. Any explicit spatial dependency has been removed from the modified equations, reducing the computational time by several orders of magnitude. Resulting 2-D dynamic intensity profiles allow investigating effects related to improper fiber coupling due to transverse misalignment between laser beam and fiber. Although the expected increased relative intensity noise (RIN) levels associated with mode partition noise are observed, other effects might have larger contributions to the total noise under specific conditions. We show that the minimum RIN level is not necessarily reached for zero misalignment, but at positions where modes with broad far-field profiles and low power experience important filtering. [ABSTRACT FROM PUBLISHER]
Published: 2003
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36. Si and GaAs 0.5μm-gate Schottky-barrier field-effect transistors

Author: K. Daetwyler, Th. O. Mohr, W. Baechtold, T. Forster, P. Wolf, and W. Walter
Subjects: Materials science, Noise measurement, business.industry, Schottky barrier, Schottky effect, Transistor, Y-factor, Noise figure, law.invention, law, Optoelectronics, Field-effect transistor, Electrical and Electronic Engineering, business, Noise (radio)
Abstract: Si and GaAs Schottky-barrier field-effect transistors with gate lengths of 0.5 μm have been experimentally realised. Noise and gain properties were measured in the microwave range up to 20 GHz. When compared with 1 μm-gate f.e.t.s, the devices show considerable improvements in gain and in noise figure. At 10 GHz, the following values were measured: Si m.e.s.f.e.t.: maximum available gain = 5.9 dB, noise figure = 5.8 dB; GaAs m.e.s.f.e.t.: maximum available gain = 12.8 dB, noise figure = 3.7 dB.
Published: 1973
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37. X- and Ku-band amplifiers with GaAs Schottky-barrier FETS

Author: W. Baechtold
Subjects: Materials science, business.industry, Amplifier, Schottky barrier, Transistor array, Y-factor, Noise figure, Ku band, Low-noise amplifier, Gallium arsenide, chemistry.chemical_compound, chemistry, Optoelectronics, business
Abstract: This paper will report on two low-power FET amplifiers: 8.2 GHz with 17.5-dB gain and 1.3-GHz bandwidth; 9.5-14.3 GHz with 8.5-dB gain.
Published: 1972
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38. An efficient system-oriented VCSEL model including 2D modal dynamics and thermal effects

Author: W. Baechtold, Daniel Erni, and M. Jungo
Subjects: Physics, Field (physics), business.industry, Orders of magnitude (temperature), law.invention, Vertical-cavity surface-emitting laser, Transverse plane, Modal, law, Laser diode rate equations, Optical cavity, Optoelectronics, Semiconductor optical gain, Statistical physics, business
Abstract: We propose a new system-oriented 2D VCSEL model, which takes into account the detailed interactions between the transverse carrier and field distributions. It shows several orders of magnitude improvement in computational efficiency compared to conventional models.

39. Q band GaAs f.e.t. amplifier and oscillator

Author: W. Baechtold
Subjects: Physics, Power gain, Range (particle radiation), business.industry, Amplifier, Transistor, law.invention, Power (physics), Q band, law, Optoelectronics, Field-effect transistor, Electrical and Electronic Engineering, business, Stripline
Abstract: GaAs field-effect transistors with a Schottky-barrier gate have been investigated in the frequency range 12–20 GHz. Measurements of the maximum available gain have shown that the devices have much higher gain in this range than has been expected. A 17 GHz oscillator having an output power of 4mW and a 4-stage 14.9GHz amplifier with 16 dB of power gain have been built using stripline technique.
Published: 1971
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40. Noise temperature in silicon in the hot electron region

Author: W. Baechtold
Subjects: Physics, Noise temperature, Lattice temperature, Condensed matter physics, Silicon, Transistor, Epitaxial silicon, chemistry.chemical_element, Electronic, Optical and Magnetic Materials, law.invention, Nuclear magnetic resonance, Carrier velocity saturation, chemistry, law, Electrical and Electronic Engineering, Saturation (magnetic), Hot electron
Abstract: The noise temperature as a function of the applied field has been measured on an epitaxial silicon layer at the frequencies 2 GHz and 4 GHz. It has been found that the experimental results are in good agreement with the theory given by Moll. It is shown that for noise calculations in silicon field-effect transistors with pronounced carrier velocity saturation the noise temperature T n versus field E may be approximated by T_{n}/T_{0} = 1 + γ (E/E_{c})^{2} with T 0 = lattice temperature, E c = saturation field, γ = const.
Published: 1971
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41. Author's reply to 'Comments on 'noise behavior of GaAs field-effect transistors with short gate length''

Author: W. Baechtold
Subjects: Physics, Noise, business.industry, Gate length, Electrical engineering, Field-effect transistor, Electrical and Electronic Engineering, business, Electronic, Optical and Magnetic Materials
Published: 1973
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42. Complementary Josephson-junction circuit: a fast flip-flop and logic gate

Author: W. Heuberger, Th. O. Mohr, W. Baechtold, and Th. Forster
Subjects: Physics, Josephson effect, Pass transistor logic, business.industry, Electrical engineering, Hardware_PERFORMANCEANDRELIABILITY, Resistor–transistor logic, law.invention, law, Logic gate, Hardware_INTEGRATEDCIRCUITS, Inverter, Equivalent circuit, Hardware_ARITHMETICANDLOGICSTRUCTURES, Electrical and Electronic Engineering, business, Flip-flop, AND gate, Hardware_LOGICDESIGN
Abstract: A logic circuit with Josephson junctions has been developed that operates as logic gate or as a flip-flop. Despite the latching-type characteristic of the Josephson tunnel junction, the complementary logic circuit is nonlatching. The test circuit has a power dissipation of 16.4 μW and a signal risetime of approximately 60 ps has been measured.
Published: 1975
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43. An improved microwave silicon MESFET

Author: W. Baechtold and P. Wolf
Subjects: Materials science, Silicon, Equivalent series resistance, Oscillation, business.industry, Transistor, Electrical engineering, chemistry.chemical_element, Condensed Matter Physics, Noise figure, Electronic, Optical and Magnetic Materials, law.invention, chemistry, law, Materials Chemistry, Optoelectronics, MESFET, Parasitic extraction, Electrical and Electronic Engineering, business, Microwave
Abstract: An improved silicon MESFET with a 1; gate is described which has a maximum frequency of oscillation of 15 GHz. The improvement over previous MESFET's has been achieved by reducing the influence of the resistance of the gate metallization and by decreasing the gate-pad parasitics. Maximum available gain MAG is now 5 dB at 7 GHz and the optimum noise figure F 0 is 5 dB at 6 GHz. Below about 6 GHz the device is conditionally unstable. Unilateral gain U up to 3 GHz is 20 dB. The investigation indicates that not all parasitics have been removed. If the series resistance of the channel in the source-gate spacing could be decreased, f max should approach 35 GHz the estimated value of the intrinsic transistor.
Published: 1971
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44. X and Ku band GaAs m.e.s.f.e.t

Author: P. Wolf, W. Baechtold, and W. Walter
Subjects: Power gain, Physics, business.industry, X band, Optoelectronics, MESFET, Field-effect transistor, Electrical and Electronic Engineering, business, Noise figure, Ku band, Noise (radio)
Abstract: A GaAs Schottky-barrier f.e.t. (m.e.s.f.e.t.) with a 1 ?m gate has been built, which is suitable for X band and Ku band applications. The unilateral power gain over the X band is above 9 dB and the noise figure is only 5 dB at 10 GHz.
Published: 1972
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