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2,351 results on '"Applied Physics"'

1. Nonlinear thermovoltage in a single-electron transistor

Author

Jukka P. Pekola, Paolo Andrea Erdman, Joonas T. Peltonen, Bibek Bhandari, Hervé Courtois, Bivas Dutta, Rosario Fazio, Fabio Taddei, NEST - Scuola Normale Superiore and Istituto Nanoscienze-CNR, Department of Applied Physics [Aalto], Aalto University, Nano-Electronique Quantique et Spectroscopie (QuNES), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Abdus Salam International Centre for Theoretical Physics [Trieste] (ICTP), Fondation Nanosciences - Grenoble, Quantum Phenomena and Devices, National Enterprise for nanoScience and nanoTechnology, National Research Council of Italy, Université Grenoble Alpes, CNR-ENEA-EURATOM Association, Centre of Excellence in Quantum Technology, QTF, Department of Applied Physics, Aalto-yliopisto, Erdman, P. A., Peltonen, J. T., Bhandari, B., Dutta, B., Courtois, H., Fazio, R., Taddei, F., and Pekola, J. P.

Subjects
Materials science, FOS: Physical sciences, 02 engineering and technology, 01 natural sciences, law.invention, law, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, Temperature difference, Sensitivity (control systems), [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, [PHYS.COND.CM-MSQHE]Physics [physics]/Condensed Matter [cond-mat]/Mesoscopic Systems and Quantum Hall Effect [cond-mat.mes-hall], [PHYS]Physics [physics], Condensed Matter - Mesoscale and Nanoscale Physics, Condensed matter physics, ta114, Transistor, Charge current, Coulomb blockade, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 021001 nanoscience & nanotechnology, Nonlinear system, 0210 nano-technology, Free parameter
Abstract

We perform direct thermovoltage measurements in a single-electron transistor, using on-chip local thermometers, both in the linear and non-linear regimes. Using a model which accounts for co-tunneling, we find excellent agreement with the experimental data with no free parameters even when the temperature difference is larger than the average temperature (far-from-linear regime). This allows us to confirm the sensitivity of the thermovoltage on co-tunneling and to find that in the non-linear regime the temperature of the metallic island is a crucial parameter. Surprisingly, the metallic island tends to overheat even at zero net charge current, resulting in a reduction of the thermovoltage., 10 pages, 4 figures

Published
2019
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2. Nonlinear dynamics of a laser diode with an injection of an optical frequency comb

Author

Yaya Doumbia, Delphine Wolfersberger, Tushar Malica, Marc Sciamanna, Krassimir Panajotov, Chaire Photonique, Laboratoire Matériaux Optiques, Photonique et Systèmes (LMOPS), CentraleSupélec-Université de Lorraine (UL)-CentraleSupélec-Université de Lorraine (UL), Department of Applied Physics and Photonics [Brussels] (TONA), Vrije Universiteit Brussel (VUB), Brussels Photonics Team, and Applied Physics and Photonics

Subjects
Materials science, Physics::Optics, 02 engineering and technology, Parameter space, 01 natural sciences, law.invention, 010309 optics, Frequency comb, SEMICONDUCTOR-LASER, LOCKING, CHAOS, GENERATION, Optics, law, 0103 physical sciences, Physics::Atomic Physics, [PHYS]Physics [physics], Laser diode, laser diode, business.industry, Nonlinear Laser Dynamics, 021001 nanoscience & nanotechnology, Laser, Atomic and Molecular Physics, and Optics, Injection locking, Nonlinear system, Semiconductor, Amplitude, 0210 nano-technology, business, Optical Frequency Combs
Abstract

International audience; We experimentally and theoretically demonstrate the variety of the nonlinear dynamics exhibited by a single frequency semiconductor laser subjected to optical injection from a frequency comb. The injection parameters (the detuning and the injection strength) and the comb properties (comb spacing and the amplitude of the injected comb lines) are varied to unveil several dynamics such as injection locking, wave-mixing, chaotic dynamics, and unlocked time-periodic dynamics corresponding to new comb solutions. The asymmetry of the injected comb is shown to modify the size of the injection locking region in the parameter space, as well as the common properties between the new comb solutions observed and the injected comb.

Published
2020
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3. Quasi-two-dimensional foam flow through and around a permeable obstacle

Author

Stéphane Santucci, Thibaud Chevalier, Natalia Shmakova, Christophe Raufaste, Antti Puisto, Mikko J. Alava, Lavrentyev Institute of Hydrodynamics (LIH), SBRAS, Department of Applied Physics and COMP CoE (Aalto University School of Science), Aalto University, Université Côte d’Azur, CNRS, INPHYNI, Nice, France, Laboratoire de Physique de l'ENS Lyon (Phys-ENS), École normale supérieure - Lyon (ENS Lyon)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, IFP Energies nouvelles (IFPEN), Institut de Physique de Nice (INPHYNI), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), Complex Systems and Materials, Department of Applied Physics, and Aalto-yliopisto

Subjects
Materials science, Computational Mechanics, Motion (geometry), Deformation (meteorology), 01 natural sciences, 010305 fluids & plasmas, Physics::Fluid Dynamics, 0103 physical sciences, Symmetry breaking, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], PLASTICITY, 010306 general physics, ComputingMilieux_MISCELLANEOUS, Fluid Flow and Transfer Processes, [PHYS]Physics [physics], HETEROGENEOUS POROUS-MEDIA, Liquid fraction, ELASTICITY, 2-DIMENSIONAL FLOW, REARRANGING DISORDERED PATTERNS, Mechanics, CIRCULAR OBSTACLE, Condensed Matter::Soft Condensed Matter, Flow (mathematics), MOBILITY, Modeling and Simulation, Obstacle, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
Abstract

We present an experimental study of a two-dimensional liquid foam, composed of a confined monolayer of bubbles, forced to flow within a model porous medium that mimics an inhomogeneous open fracture. It consists of a Hele-Shaw cell with a single localized constriction-like defect that reduces locally its gap and thus its permeability. Taking advantage of the possibility to directly visualize and follow the bubbles, we compute the bubble velocity field by image correlation analysis, as well as the bubble deformation field, through eccentricity measurements obtained by fitting each bubble with an ellipse. The defect acting as a permeable obstacle can strongly disturb the foam flow; we investigate here the influence of its geometry (height, size, and shape) on the average steady-state flow of foams of various liquid content, and specifically the motion and deformation of their elementary components, the bubbles. In the frame of the flowing foam, we can observe a recirculation around the obstacle, characterized by a multipolar velocity field. Its complex structure displays a strong fore-aft asymmetry, with an extended region downstream the constriction, where the foam velocity can be much larger than the imposed driving one. This overshoot was already revealed for nonpermeable obstacles, but here we show that its extent and intensity are associated to the bubble deformation and depend strongly and nontrivially on both the geometry of the constriction as well as the liquid fraction of the foam.

Published
2020
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4. Atomic structure and origin of chirality of DNA-stabilized silver clusters

Author

Xi Chen, Mauro Boero, Olga Lopez-Acevedo, Department of Applied Physics - Aalto University (Department of Applied Physics - Aalto University), Université de Strasbourg (UNISTRA), Universidad de Antioquia = University of Antioquia [Medellín, Colombia], Department of Applied Physics, University of Strasbourg, Universidad de Antioquia, Aalto-yliopisto, and Aalto University

Subjects
[PHYS]Physics [physics], Materials science, Physics and Astronomy (miscellaneous), PSEUDOPOTENTIALS, NANOCLUSTERS, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Circular dichroism spectra, 01 natural sciences, Fluorescence, 0104 chemical sciences, Nanoclusters, chemistry.chemical_compound, chemistry, Chemical physics, [CHIM]Chemical Sciences, General Materials Science, 0210 nano-technology, Chirality (chemistry), DNA, ComputingMilieux_MISCELLANEOUS, APPROXIMATION
Abstract

DNA-stabilized silver clusters (Ag:DNAs) have attracted much attention due to their unique sequence-dependent fluorescence and many potential applications; however, the understandings of their atomic structures and functional properties are still limited, which hamper the further development of the novel nanoclusters. Using the advanced computational methods, we propose three atomistic models for the Ag:DNAs, which all contain a four-electron silver core with a two-row planar shape stabilized by the nitrogen atoms in the DNA. By comparing experimental and time-dependent density functional theory-simulated circular dichroism spectra, we have confirmed that these core structures should commonly exist in the Ag:DNAs. We then analyze the electronic and optical properties of the clusters and discover that the silver to DNA transitions have essential contributions to the chiroptical properties of the clusters.

Published
2020
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5. Frequency comb customization by controlling the optical injection dynamics

Author

Tushar Malica, Yaya Doumbia, Krassimir Panajotov, Delphine Wolfersberger, Marc Sciamanna, Chaire Photonique, Laboratoire Matériaux Optiques, Photonique et Systèmes (LMOPS), CentraleSupélec-Université de Lorraine (UL)-CentraleSupélec-Université de Lorraine (UL), Department of Applied Physics and Photonics [Brussels] (TONA), Vrije Universiteit Brussel (VUB), Sciamanna, Marc, Michalzik, Rainer, Panajotov, Krassimir, Hofling, Sven, Brussels Photonics Team, Applied Physics and Photonics, and Doumbia, Yaya

Subjects
Materials science, animal structures, Physics::Optics, SURFACE-EMITTING LASERS, SEMICONDUCTOR-LASER, NONLINEAR DYNAMICS, SUBJECT, STABILITY, LOCKING, 02 engineering and technology, 01 natural sciences, [PHYS] Physics [physics], law.invention, 010309 optics, Frequency comb, Fundamental difference, law, 0103 physical sciences, Physics::Atomic Physics, Times periodic dynamics, Optical injection locking, [PHYS]Physics [physics], choas, business.industry, Dynamics (mechanics), fungi, Single-mode optical fiber, 021001 nanoscience & nanotechnology, Laser, Nonlinear system, Semiconductor, Optoelectronics, 0210 nano-technology, business
Abstract

International audience; This work reports on numerical analysis of the nonlinear dynamics of a semiconductor laser subject to an optical injection with a frequency comb. We identified the fundamental difference between the single mode injection and frequency comb injection. By varying the injection parameters (detuning and injection ratio), the results show that the slave laser is able to reproduce the injected frequency comb (new comb) in different parameters regions. The appearance of the new comb depends on the number of injected comb lines for fixed comb properties.

Published
2020

6. Wavelength-Selective Nonlinear Imaging and Photo-Induced Cell Damage by Dielectric Harmonic Nanoparticles

Author

Florian Riporto, Vasyl Kilin, John A. Capobianco, Yannick Mugnier, Christophe Mas, Gabriel Campargue, Jean-Pierre Wolf, Alice Vieren, Alfred Vogel, Davide Staedler, Ina Fureraj, Tarek Sabri, John Collins, Sim Sakong, Luigi Bonacina, Group of Applied Physics - Biophotonics [Geneva] (GAP-Biophotonics), Group of Applied Physics [Geneva] (GAP), University of Geneva [Switzerland]-University of Geneva [Switzerland], Laboratoire SYstèmes et Matériaux pour la MEcatronique (SYMME), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Ecole Polytechnique Fédérale de Lausanne (EPFL), University of Geneva [Switzerland], Marqueurs pronostiques et facteurs de régulations des pathologies cardiaques et vasculaires - UFC ( EA 3920) (PCVP / CARDIO), Centre Hospitalier Régional Universitaire de Besançon (CHRU Besançon)-Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)

Subjects
Materials science, Nanothermometry, General Physics and Astronomy, Nanoparticle, Gadolinium, 02 engineering and technology, Dielectric, ddc:500.2, Upconversion nanoparticles, 010402 general chemistry, 01 natural sciences, Fluorides, chemistry.chemical_compound, medicine, Humans, High harmonic generation, General Materials Science, Cell damage, ComputingMilieux_MISCELLANEOUS, Bismuth ferrite, Photoinduced cell damage, Harmonic generation, business.industry, General Engineering, Silicon Dioxide, 021001 nanoscience & nanotechnology, medicine.disease, 0104 chemical sciences, Wavelength, chemistry, Harmonic, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Nanoparticles, Optoelectronics, Harmonic nanoparticles, 0210 nano-technology, business, Decoupling (electronics)
Abstract

We introduce a nonlinear all-optical theranostics protocol based on the excitation wavelength decoupling between imaging and photoinduced damage of human cancer cells labeled by bismuth ferrite (BFO) harmonic nanoparticles (HNPs). To characterize the damage process, we rely on a scheme for in situ temperature monitoring based on upconversion nanoparticles: by spectrally resolving the emission of silica coated NaGdF4:Yb3+/Er3+ nanoparticles in close vicinity of a BFO HNP, we show that the photointeraction upon NIR-I excitation at high irradiance is associated with a temperature increase >100 °C. The observed laser–cell interaction implies a permanent change of the BFO nonlinear optical properties, which can be used as a proxy to read out the outcome of a theranostics procedure combining imaging at 980 nm and selective cell damage at 830 nm. The approach has potential applications to monitor and treat lesions within NIR light penetration depth in tissues.

Published
2020
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7. Elemental Identification by Combining Atomic Force Microscopy and Kelvin Probe Force Microscopy

Author

Adam S. Foster, Peter Liljeroth, Fabian Schulz, Ondrej Krejci, Ari P. Seitsonen, Juha Ritala, Department of Applied Physics [Aalto], Aalto University, COMP Centre of Excellence, Département de Chimie, École Normale Supérieure, WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University (KU), Department of Applied Physics, Surfaces and Interfaces at the Nanoscale, École normale supérieure, and Aalto-yliopisto

Subjects
Materials science, van der Waals density functional theory, General Physics and Astronomy, 02 engineering and technology, noncontact atomic force microscopy (nc-AFM), 01 natural sciences, Kelvin probe force microscopy (KPFM), Article, Overlayer, Condensed Matter::Materials Science, 0103 physical sciences, Microscopy, Monolayer, Physics::Atomic and Molecular Clusters, Molecule, General Materials Science, hexagonal boron nitride, 010306 general physics, Kelvin probe force microscope, [PHYS]Physics [physics], ta114, General Engineering, 021001 nanoscience & nanotechnology, Bond length, Chemical physics, elemental contrast, 0210 nano-technology, Volta potential, Chemical fingerprinting
Abstract

International audience; There are currently no experimental techniques that combine atomic-resolution imaging with elemental sensitivity and chemical finger-printing on single molecules. The advent of using molecular-modified tips in noncontact atomic force microscopy (nc-AFM) has made it possible to image (planar) molecules with atomic resolution. However, the mechanisms responsible for elemental contrast with passivated tips are not fully understood. Here, we investigate elemental contrast by carrying out both nc-AFM and Kelvin probe force microscopy (KPFM) experiments on epitaxial monolayer hexagonal boron nitride (hBN) on Ir(111). The hBN overlayer is inert, and the in-plane bonds connecting nearest-neighbor boron and nitrogen atoms possess strong covalent character and a bond length of only ∼1.45 Å. Nevertheless, constant-height maps of both the frequency shift Δf and the local contact potential difference exhibit striking sublattice asymmetry. We match the different atomic sites with the observed contrast by comparison with nc-AFM image simulations based on the density functional theory optimized hBN/Ir(111) geometry, which yields detailed information on the origin of the atomic-scale contrast.

Published
2018
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8. Optical Feedback Sensitivity of a Semiconductor Ring Laser with Tunable Directionality

Author

Guy Van der Sande, Guy Verschaffelt, Mulham Khoder, Applied Physics, Applied Physics and Photonics, and Basic (bio-) Medical Sciences

Subjects
lcsh:Applied optics. Photonics, Materials science, business.industry, lcsh:TA1501-1820, Physics::Optics, Semiconductor ring laser, Laser, Atomic and Molecular Physics, and Optics, Optical reflection, law.invention, Wavelength, laser stability, law, semiconductor ring laser, Directionality, Optoelectronics, Radiology, Nuclear Medicine and imaging, 10.3390/photonics6040112, Photonics, business, Reduction (mathematics), Instrumentation, Sensitivity (electronics), optical feedback
Abstract

We discuss the sensitivity to optical feedback of a semiconductor ring laser that is made to emit in a single-longitudinal mode by applying on-chip filtered optical feedback in one of the directional modes. The device is fabricated on a generic photonics integration platform using standard components. By varying the filtered feedback strength, we can tune the wavelength and directionality of the laser. Beside this, filtered optical feedback results in a limited reduction of the sensitivity for optical feedback from an off-chip optical reflection when the laser is operating in the unidirectional regime.

Published
2019

9. Reduced nonradiative recombination in semipolar green-emitting III-N quantum wells with strain-reducing AlInN buffer layers

Author

Andreas Hangleiter, Heiko Bremers, Florian Tendille, Philippe Vennéguès, Philippe De Mierry, Philipp Henning, Philipp Horenburg, Jesús Zúñiga-Pérez, Uwe Rossow, Institute of Applied Physics [Braunschweig], Technische Universität Braunschweig [Braunschweig], Centre de recherche sur l'hétéroepitaxie et ses applications (CRHEA), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), Institute of Applied Physics, and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA)

Subjects
010302 applied physics, Materials science, Photoluminescence, Physics and Astronomy (miscellaneous), Strain (chemistry), business.industry, Relaxation (NMR), 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Buffer (optical fiber), Lattice mismatch, [SPI]Engineering Sciences [physics], 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Optoelectronics, 0210 nano-technology, business, Layer (electronics), Quantum well, Recombination, ComputingMilieux_MISCELLANEOUS
Abstract

Using strain-reducing partially relaxed AlInN buffer layers, we observe reduced nonradiative recombination in semipolar green-emitting GaInN/GaN quantum wells. Since strain is a key issue for the formation of defects that act as nonradiative recombination centers, we aim to reduce the lattice mismatch between GaInN and GaN by introducing an AlInN buffer layer that can be grown lattice-matched along one of the in-plane directions of GaN, even in the semipolar ( 11 2 ¯ 2 ) orientation. With the increasing thickness, the buffer layer shows partial relaxation in one direction and thereby provides a growth template with reduced lattice mismatch for the subsequent GaInN quantum wells. Time-resolved photoluminescence measurements show reduced nonradiative recombination for the structures with a strain-reducing buffer layer.Using strain-reducing partially relaxed AlInN buffer layers, we observe reduced nonradiative recombination in semipolar green-emitting GaInN/GaN quantum wells. Since strain is a key issue for the formation of defects that act as nonradiative recombination centers, we aim to reduce the lattice mismatch between GaInN and GaN by introducing an AlInN buffer layer that can be grown lattice-matched along one of the in-plane directions of GaN, even in the semipolar ( 11 2 ¯ 2 ) orientation. With the increasing thickness, the buffer layer shows partial relaxation in one direction and thereby provides a growth template with reduced lattice mismatch for the subsequent GaInN quantum wells. Time-resolved photoluminescence measurements show reduced nonradiative recombination for the structures with a strain-reducing buffer layer.

Published
2019
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10. Controlling All‐Optical Helicity‐Dependent Switching in Engineered Rare‐Earth Free Synthetic Ferrimagnets

Author

Russell P. Cowburn, Gregory Malinowski, Eduardo Martínez, Unai Atxitia, Michel Hehn, Jung-Wei Liao, Victor Raposo, Dorothée Petit, Liam O'Brien, Pierre Vallobra, Tarun Vemulkar, Stéphane Mangin, Cavendish Laboratory, University of Cambridge [UK] (CAM), Institut Jean Lamour (IJL), Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Department of Physics - University of Liverpool, University of Liverpool, Department of Physics [Berlin], Freie Universität Berlin, Department of Applied Physics of the Faculty of Science University of Salamanca, Department of Applied physics of the Faculty of Science University of Salamanca, IMPACT N4S, and ANR-15-IDEX-0004,LUE,Isite LUE(2015)

Subjects
Materials science, Magnetism, General Chemical Engineering, General Physics and Astronomy, Medicine (miscellaneous), 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Biochemistry, Genetics and Molecular Biology (miscellaneous), Condensed Matter::Materials Science, ferromagnets, Ferrimagnetism, Curie, Computational physics, Antiferromagnetism, General Materials Science, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], lcsh:Science, ComputingMilieux_MISCELLANEOUS, Full Paper, Condensed matter physics, 500 Naturwissenschaften und Mathematik::530 Physik::530 Physik, General Engineering, Full Papers, 021001 nanoscience & nanotechnology, Helicity, 0104 chemical sciences, synthetic ferrimagnets, Ferromagnetism, Femtosecond, Curie temperature, lcsh:Q, Condensed Matter::Strongly Correlated Electrons, 2202.08 Magnetismo, 0210 nano-technology, all‐optical switching
Abstract

All‐optical helicity‐dependent switching in ferromagnetic layers has revealed an unprecedented route to manipulate magnetic configurations by circularly polarized femtosecond laser pulses. In this work, rare‐earth free synthetic ferrimagnetic heterostructures made from two antiferromagnetically exchange coupled ferromagnetic layers are studied. Experimental results, supported by numerical simulations, show that the designed structures enable all‐optical switching which is controlled, not only by light helicity, but also by the relative Curie temperature of each ferromagnetic layer. Indeed, through the antiferromagnetic exchange coupling, the layer with the larger Curie temperature determines the final orientation of the other layer and so the synthetic ferrimagnet. For similar Curie temperatures, helicity‐independent back switching is observed and the final magnetic configuration is solely determined by the initial magnetic state. This demonstration of electrically‐detected, optical control of engineered rare‐earth free heterostructures opens a novel route toward practical opto‐spintronics., All‐optical helicity‐dependent switching in synthetic ferrimagnetic samples made of two exchanged coupled ferromagnetic layers is shown to depend on the respective Curie temperature of each layer. By varying the CoFeB layer thickness, its Curie temperature can be tuned. Consequently, the switching is set not only by the light helicity but also by the CoFeB thickness.

Published
2019
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11. Electro-Absorption Modulator Vertically Integrated on a VCSEL: Microstrip-Based High-Speed Electrical Injection on Top of a BCB Layer

Author

Aurélie Lecestre, Hugo Thienpont, Christophe Viallon, Ayad Ghannam, Guilhem Almuneau, Ludovic Marigo-Lombart, Alexandre Rumeau, Alexandre Arnoult, Krassimir Panajotov, Laurent Mazenq, Équipe Photonique (LAAS-PHOTO), Laboratoire d'analyse et d'architecture des systèmes (LAAS), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées, Équipe Microondes et Opto-microondes pour Systèmes de Télécommunications (LAAS-MOST), Service Instrumentation Conception Caractérisation (LAAS-I2C), Service Techniques et Équipements Appliqués à la Microélectronique (LAAS-TEAM), 3DiS Technologies, Department of Applied Physics and Photonics [Brussels] (TONA), Vrije Universiteit Brussel (VUB), Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT), Applied Physics and Photonics, and Brussels Photonics Team

Subjects
Materials science, Electro-absorption modulator, 02 engineering and technology, VCSEL, Microstrip, Vertical-cavity surface-emitting laser, [SPI.MAT]Engineering Sciences [physics]/Materials, chemistry.chemical_compound, 020210 optoelectronics & photonics, Benzocyclobutene, High-speed modulation, high-speed modulation, 0202 electrical engineering, electronic engineering, information engineering, electro-absorption modulator, Output impedance, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, BCB, business.industry, Coplanar waveguide, Atomic and Molecular Physics, and Optics, Electrical contacts, chemistry, Modulation, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Optoelectronics, business, BENZOCYCLOBUTENE, FABRICATION, PASSIVATION, FILMS
Abstract

International audience; Vertical-cavity surface-emitting lasers with vertically integrated electro-absorption modulators (EAM-VCSELs) potentially can reach higher modulation bandwidths than directly current-modulated VCSELs. The aforementioned device modulation capabilities are, however, currently restricted by their electrical contact parasitics. It, thus, becomes critical to optimize their access line to improve performance. In this paper, we numerically and experimentally demonstrate that a microstrip (MS) access line using a planarized benzocyclobutene (BCB) layer exhibits improved high-frequency characteristics compared to the coplanar waveguide (CPW) access line used to-date, since it reduces the losses induced by the doped substrates. We also use this opportunity to introduce an innovative technique for BCB layer planarization, which is not only compatible with the EAM-VCSEL double-mesa structure, but is also independent of the device pitch. The resulting BCB layer dielectric permittivity and losses are measured up to 100 GHz, and a side-by-side comparison of the electrical response of three-electrodes MS and CPW access lines is subsequently carried out. Finally, using the measured pad and access line RF responses and the EAM modulation characteristics, the devices with MS access are shown to be no longer limited by their electrode parasitics, but by the modulator internal impedance.

Published
2019
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12. Simultaneous monitoring of structural changes and phase distribution of LiFePO4 along the cathode thickness of Li metal polymer battery

Author

Maria Valeria Blanco, Marc Deschamps, Federico Cova, Yves Watier, Didier Devaux, Lucille Quazuguel, Renaud Bouchet, Anna-Maija Valtavirta, Carlos Cosculluela, Margaud Lecuyer, European Synchroton Radiation Facility [Grenoble] (ESRF), Matériaux Interfaces ELectrochimie (MIEL), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces (LEPMI), Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Department of Applied Physics [Aalto], Aalto University, Department of Physics [Helsinki], Falculty of Science [Helsinki], University of Helsinki-University of Helsinki, Helsinki Institute of Physics (HIP), University of Helsinki, European Synchrotron Radiation Facility (ESRF), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Aalto University (A?), Blue Solutions, Odet, Ergue Gaberic, 29500 Quimper, France, European Synchrotron Radiation Facility, Institut national de physique nucléaire et de physique des particules, Department of Applied Physics, Blue Solutions, and Aalto-yliopisto

Subjects
Battery (electricity), Materials science, chemistry.chemical_element, 02 engineering and technology, Electrolyte, 010402 general chemistry, 01 natural sciences, Electrochemical cell, law.invention, LiFePO4, Li polymer battery, operando XRD, law, Phase (matter), Materials Chemistry, Electrochemistry, Composite material, Separator (electricity), Renewable Energy, Sustainability and the Environment, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Cathode, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, [CHIM.POLY]Chemical Sciences/Polymers, chemistry, Electrode, Lithium, XRD-CT, 0210 nano-technology, [CHIM.OTHE]Chemical Sciences/Other
Abstract

Probing the structural changes that electrode materials undergo during electrochemical cycling while monitoring their spatial distribution within the volume gives valuable insights on dynamic processes, i.e. side reactions and evolution of phase migration barriers, often associated to capacity and power limitation. In this work, we present an electrochemical cell to perform spatial and time resolved operando synchrotron X-ray diffraction on Lithium (Li) metal polymer batteries operating at 80 °C. A 3.2 mm diameter battery made of a Li metal anode, a LiFePO4 based cathode, and a solid polymer electrolyte acting as separator, is placed inside a glass-based casing and cycled at a beamline. The cylindrical cell geometry with its small size enables to follow the phase transformations occurring at different states of charge and at different cathode heights. It is possible to create spatially resolved phase distribution plots and to differentiate active material structural changes occurring close to the interface with the electrolyte from those at the current collector vicinity. The results provide a direct observation of the Li diffusion in the LiFePO4 and FePO4 phase distribution. In addition, synchrotron X-ray diffraction computed tomography (XRD-CT) measurements were performed to obtain phase distribution maps at different heights of the battery assembly.

Published
2020
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13. High frequency characterization of a vertical electro-absorption modulator for data communications

Author

Ludovic Marigo-Lombart, Christophe Viallon, Guilhem Almuneau, Olivier Gauthier-Lafaye, Alexandre Rumeau, Krassimir Panajotov, Antoine Monmayrant, Hugo Thienpont, Équipe Photonique (LAAS-PHOTO), Laboratoire d'analyse et d'architecture des systèmes (LAAS), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées, Équipe Microondes et Opto-microondes pour Systèmes de Télécommunications (LAAS-MOST), Service Instrumentation Conception Caractérisation (LAAS-I2C), Department of Applied Physics and Photonics [Brussels] (TONA), Vrije Universiteit Brussel (VUB), IEEE, Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT), Faculty of Engineering, Applied Physics and Photonics, and Brussels Photonics Team

Subjects
Signal processing, Materials science, Computer Networks and Communications, 02 engineering and technology, VCSEL, 01 natural sciences, Vertical integration, Vertical-cavity surface-emitting laser, law.invention, [SPI.MAT]Engineering Sciences [physics]/Materials, law, 0103 physical sciences, Electro-absorption modulator, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Instrumentation, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, business.industry, modulator, electro-absorption, 021001 nanoscience & nanotechnology, Atomic and Molecular Physics, and Optics, Characterization (materials science), Photodiode, high-frequency, Modulation, Optical fiber coupling, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Optoelectronics, Radio frequency, 0210 nano-technology, business
Abstract

This paper describes the high-frequency characterizations of a vertical electro-absorption modulator (EAM) to ensure its monolithic integration onto a VCSEL for data communications. Splitting the emitting and the modulating parts is an attractive approach compared to directly current-modulated VCSEL since it releases the intrinsic limitations due to carriers dynamics that occurs in such VCSEL device. It is, in this aim, utmost to thoroughly characterize and understand the properties and performances of the vertically integrated EAM under high frequency operation, as it will be decisive for the application of EAM-VCSEL to very high data-rate communications. EAM measurements, presented up to 40 GHz, require a precise control of the optical fiber coupling and a precise evaluation of the injection losses over the full frequency range.

Published
2018

14. Tuning the Emission of Micro Ring Lasers Using Integrated Optical Feedback: Experiments and Traveling Wave Simulations

Author

Mindaugas Radziunas, Guy Verschaffelt, Vasile Tronciu, Jan Danckaert, Mulham Khoder, Brussels Photonics Team, Applied Physics and Photonics, Faculty of Engineering, Physics, and Applied Physics

Subjects
Materials science, business.industry, Physics::Optics, Ring (chemistry), Laser, Semiconductor laser theory, law.invention, Electronic, Optical and Magnetic Materials, Wavelength, Optics, law, Mechanics of Materials, Traveling wave, business
Abstract

We investigate the tuning of the wavelength of a micro-ring laser using on-chip feedback. We demonstrate tuning experimentally and numerically. The results also show that traveling-wave model is suitable for simulating complex laser configurations.

Published
2018
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15. Using on-Chip Feedback to Stabilize the Emission of Micro Ring Laser in the Presence of Reflections

Author

Mulham Khoder, Applied Physics and Photonics, Faculty of Engineering, Brussels Photonics Team, and Applied Physics

Subjects
Materials science, business.industry, Mechanics of Materials, Optoelectronics, Ring laser, business, Electronic, Optical and Magnetic Materials
Abstract

We propose to integrate a feedback section on-chip with micro ring laser to stabilize the emission of micro ring laser in the presence of reflections. The results show that feedback can decrease the undesired effects of the reflections.

Published
2018

16. Experimental 1.5-1.6 μm Water Line List at 1950 K

Author

Oleg L. Polyansky, Aleksandra Foltynowicz, Nikolai F. Zobov, Sergey N. Yurchenko, Alexandra C. Johansson, Aleksandra A. Kyuberis, Amir Khodabakhsh, Florian M. Schmidt, Jonathan Tennyson, Lucile Rutkowski, Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Department of Physics [Umeå], Umeå University, Insitute of Applied Physics, Russian Academy of Sciences, Institute of Applied Physics, Russian Academy of Sciences, University College of London [London] (UCL), OSA, Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], Absorption of water, Materials science, Absorption spectroscopy, Analytical chemistry, Optical frequency comb spectroscopy, Physics::Optics, 01 natural sciences, Fourier transform spectroscopy, 010309 optics, Line list, Frequency comb, Attenuation coefficient, 0103 physical sciences, Molecular physics, Spectroscopy, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS
Abstract

We demonstrate a high-temperature water absorption spectrum measured in a flame using cavity-enhanced frequency comb-based Fourier transform spectroscopy. The retrieved transition intensities and frequencies are assigned using the POKAZATEL line list.

Published
2018
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17. Atomic Scale Formation Mechanism of Edge Dislocation Relieving Lattice Strain in a GeSi overlayer on Si(001)

Author

Laurent Pizzagalli, Emile Maras, Tapio Ala-Nissila, Hannes Jónsson, CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut Pprime (PPRIME), Université de Poitiers-ENSMA-Centre National de la Recherche Scientifique (CNRS), Department of Applied Physics and COMP CoE (Aalto University School of Science), Aalto University School of Science, Division of Energy and Mechanical Engineering Department of Technology and Built Environment, University of Gsyle, Raunvísindadeild (HÍ), Faculty of Physical Sciences (UI), Verkfræði- og náttúruvísindasvið (HÍ), School of Engineering and Natural Sciences (UI), Háskóli Íslands, University of Iceland, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Aalto University, Université de Poitiers-Centre National de la Recherche Scientifique (CNRS)-ENSMA, Department of Applied Physics, Université de Poitiers, and Aalto-yliopisto

Subjects
Surface (mathematics), Materials science, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Nucleation, lcsh:Medicine, Líkindafræði, 02 engineering and technology, Edge (geometry), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Two-dimensional materials, 01 natural sciences, Atomic units, Article, Overlayer, Glide plane, Surfaces, interfaces and thin films, Efnafræði, 0103 physical sciences, lcsh:Science, 010306 general physics, ComputingMilieux_MISCELLANEOUS, Multidisciplinary, Condensed matter physics, lcsh:R, 021001 nanoscience & nanotechnology, Potential energy, lcsh:Q, Density functional theory, 0210 nano-technology
Abstract

Understanding how edge misfit dislocations (MDs) form in a GeSi/Si(001) film has been a long standing issue. The challenge is to find a mechanism accounting for the presence of these dislocations at the interface since they are not mobile and cannot nucleate at the surface and glide towards the interface. Furthermore, experiments can hardly detect the nucleation and early stages of growth because of the short time scale involved. Here we present the first semi-quantitative atomistic calculation of the formation of edge dislocations in such films. We use a global optimization method and density functional theory calculations, combined with computations using potential energy functions to identify the best mechanisms. We show that those previously suggested are relevant only for a low film strain and we propose a new mechanism which accounts for the formation of edge dislocations at high film strain. In this one, a 60° MD nucleates as a “split” half-loop with two branches gliding on different planes. One branch belongs to the glide plane of a complementary 60° MD and therefore strongly favors the formation of the complementary MD which is immediately combined with the first MD to form an edge MD., This work has been supported in part by the Academy of Finland through its COMP CoE (T.A.-N., nos 251748 and 284621) and FiDiPro (E.M. and H.J., no. 263294) grants. We acknowledge computational resources provided by the Aalto Science-IT project and CSC IT Center for Science Ltd in Espoo, Finland. E.M. wishes to thank Oleg Trushin, David Rodney and Emmanuel Clouet for helpful discussions.

Published
2017
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18. Impact of interaction range and curvature on crystal growth of particles confined to spherical surfaces

Author

Ppam Paul van der Schoot, Gert-Jan Both, Stefan Paquay, Soft Matter and Biological Physics, Applied Physics and Science Education, and Applied Physics

Subjects
cond-mat.soft, Materials science, Condensed matter physics, Isotropy, FOS: Physical sciences, Crystal growth, 02 engineering and technology, Bending, Condensed Matter - Soft Condensed Matter, 021001 nanoscience & nanotechnology, Curvature, 01 natural sciences, Stress (mechanics), Crystal, Classical mechanics, Phase (matter), 0103 physical sciences, Soft Condensed Matter (cond-mat.soft), 010306 general physics, 0210 nano-technology, Scaling
Abstract

When colloidal particles form a crystal phase on a spherical template, their packing is governed by the effective interaction between them and the elastic strain of bending the growing crystal. For example, if growth commences under appropriate conditions, and the circular crystal that forms reaches a critical size, growth continues by incorporation of defects to alleviate elastic strain. Recently it was found experimentally that, if defect formation is somehow not possible, the crystal instead continues growing in ribbons that protrude from the original crystal. Here we report on computer simulations in which we observe both the formation of ribbons at short interaction ranges and packings that incorporate defects if the interaction is longer-ranged. The ribbons only form above some critical crystal size, below which the nucleus is roughly spherically shaped. We find that the scaling of the critical crystal size differs slightly from the one proposed by the Manoharan group, and reason this is because the actual process is a two-step heterogeneous nucleation of ribbons on top of roughly circular crystals., 24 pages, 11 figures

Published
2017
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19. Fabrication, detection and operation of a three-dimensional nanomagnetic conduit

Author

Alexander Welbourne, Dédalo Sanz-Hernández, Reinoud Lavrijsen, Jung-Wei Liao, Ruben F. Hamans, Amalio Fernández-Pacheco, Applied Physics, Physics of Nanostructures, Photo Conversion Materials, LaserLaB - Energy, Applied Physics and Science Education, Fernández-Pacheco, Amalio [0000-0002-3862-8472], and Apollo - University of Cambridge Repository

Subjects
Materials science, Nanostructure, Fabrication, Nanowire, General Physics and Astronomy, FOS: Physical sciences, Nanotechnology, 02 engineering and technology, Substrate (printing), domain wall, 3D nanoprinting, 01 natural sciences, Electrical conduit, magneto-optical Kerr effect, 0103 physical sciences, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), General Materials Science, dark field, 010302 applied physics, Condensed Matter - Mesoscale and Nanoscale Physics, General Engineering, 021001 nanoscience & nanotechnology, Characterization (materials science), Domain wall (magnetism), Physical vapor deposition, nanomagnetism, 0210 nano-technology, racetrack memory
Abstract

Three-dimensional (3D) nanomagnetic devices such as the vertical racetrack memory have attracted a huge interest due to their potential for memory and logic applications. However, their implementation has not been realised due to great challenges regarding fabrication and characterisation of 3D nanostructures. Here, we show a 3D nanomagnetic system created by 3D nano-printing and physical vapour deposition, which acts a conduit for domain walls. Domains formed at the substrate level are injected into a 3D nanowire, where they are controllably trapped using vectorial magnetic fields. A dark-field magneto-optical method for parallel, independent measurement of different regions in individual 3D nanostructures is also demonstrated. This work opens a new route for the advanced study and exploitation of 3D nanomagnetic systems., 21 pages, 4 figures

Published
2017
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20. Designing an efficient rectifying cut-wire metasurface for electromagnetic energy harvesting

Author

Jan Danckaert, Philippe Tassin, Vincent Ginis, Gabin Thibaut Oumbe Tekam, Faculty of Sciences and Bioengineering Sciences, Applied Physics, Applied Physics and Photonics, Faculty of Engineering, Teacher Education, and Physics

Subjects
010302 applied physics, Materials science, Physics and Astronomy (miscellaneous), business.industry, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Power (physics), 0103 physical sciences, Optoelectronics, 0210 nano-technology, business, Absorption (electromagnetic radiation), Energy harvesting, Microwave, Energy (signal processing), p–n diode, Diode, Power density
Abstract

Electromagnetic energy harvesting, i.e., capturing energy from ambient microwave signals, may become an essential part in extending the battery lifetime of wearable devices. Here, we present a design of a microwave energy harvester based on a cut-wire metasurface with an integrated PN junction diode. The cut wire with a quasistatic electric-dipole moment is designed to have a resonance at 6.75 GHz, leading to a substantial cross-section for absorption. The external microwaves create a unidirectional current through the rectifying action of the integrated diode. Using an electrical-circuit model, we design the operating frequency and the resistive load of the cut wire. Subsequently, by optimizing our design using full-wave numerical simulations, we obtain an energy harvesting efficiency of 50% for incident power densities in agreement with the typical power density of WiFi signals. Finally, we study the effect of connecting adjacent unit cells of the metasurface in parallel by a thin highly inductive wire and we demonstrate that this allows for the collection of current from all individual cells, while the microwave resonance of the unit cell is not significantly altered, thus solving the wiring problem that arises in many nonlinear metamaterials.

Published
2017
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21. Shockwave-assisted laser filament conductivity

Author

Denis Mongin, Thomas Produit, Jérôme Kasparian, Guillaume Schimmel, Jean-Pierre Wolf, Elise Schubert, GAP-Group of Applied Physics, University of Geneva [Switzerland], Institute for Environmental Sciences [Geneva] ( ISE ), FET OPEN LLR, European Project : 291201,EC:FP7:ERC,ERC-2011-ADG_20110209,FILATMO ( 2012 ), European Project : 737033,LLR, Group of Applied Physics [Geneva] (GAP), Université de Genève = University of Geneva (UNIGE), Institute for Environmental Sciences [Geneva] (ISE), European Project: 291201,EC:FP7:ERC,ERC-2011-ADG_20110209,FILATMO(2012), and European Project: 737033,LLR

Subjects
Shock wave, Materials science, Physics and Astronomy (miscellaneous), Décharge, Femtoseconde, Guidage, Femtosecond, Laser, FOS: Physical sciences, ddc:500.2, Conductivity, 01 natural sciences, law.invention, High voltage, 010309 optics, Protein filament, Filamentation, law, Electric field, 0103 physical sciences, Onde de choc, 010306 general physics, plasma, ddc:333.7-333.9, [PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], [ PHYS.PHYS.PHYS-OPTICS ] Physics [physics]/Physics [physics]/Optics [physics.optics], nonlinear optics, Plasma, shock waves, Physics - Plasma Physics, Shockwave, filamentation, Plasma Physics (physics.plasm-ph), Plasma channel, Discharge, Guiding, Atomic physics, Haute tension, Physics - Optics, Optics (physics.optics)
Abstract

We investigate the influence of ultrashort laser filaments on high-voltage discharges and spark-free unloading at various repetition rates and wind conditions. For electric fields well below, close to and above the threshold for discharges, we respectively observe remote spark-free unloading, discharge suppression, and discharge guiding. These effects rely on an indirect consequence of the thermal deposition, namely the fast dilution of the ions by the shockwave triggered by the filament at each laser shot. This dilution drastically limits recombination and increases the plasma channel conductivity that can still be non-negligible after tens or hundreds of milliseconds. As a result, the charge flow per pulse is higher at low repetition rates., Comment: 8 pages, 4 figures

Published
2017
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22. Oxide-confined VCSELs fabricated with a simple self-aligned process flow

Author

Ludovic Marigo-Lombart, Guilhem Almuneau, Stephane Calvez, Krassimir Panajotov, Hugo Thienpont, Alexandre Arnoult, Department of Applied Physics and Photonics [Brussels] (TONA), Vrije Universiteit Brussel (VUB), Équipe Photonique (LAAS-PHOTO), Laboratoire d'analyse et d'architecture des systèmes (LAAS), Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT), Service Techniques et Équipements Appliqués à la Microélectronique (LAAS-TEAM), Applied Physics and Photonics, Faculty of Engineering, Brussels Photonics Team, Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), and Université Fédérale Toulouse Midi-Pyrénées

Subjects
Materials science, Fabrication, self-aligned, oxidation, Nanotechnology, 02 engineering and technology, 7. Clean energy, 01 natural sciences, VCSEL, Vertical-cavity surface-emitting laser, law.invention, 020210 optoelectronics & photonics, Etching (microfabrication), law, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Materials Chemistry, Wafer, Electrical and Electronic Engineering, Lithography, 010302 applied physics, business.industry, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Self-aligned, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Optoelectronics, Dry etching, Photolithography, Photonics, business, lasers
Abstract

International audience; We propose a simplified and easier fabrication process flow for the manufacturing of AlOx-confined VCSELs based on combining the oxidation step with a self-aligned process, allowing the mesa etching and two successive lift-off steps based on a single lithography step. The electro-optical confinement achieved by standard lateral oxidation enables a low threshold and a single mode behaviour for the VCSEL. This simplified process can largely improve VCSEL manufacturing by reducing the processing time and costs compared to the standard VCSEL process. Introduction: Vertical-cavity surface-emitting lasers (VCSEL) have become the preferred light sources in many photonic systems, enabling short-link interconnections [1] but also in other emerging mass-market applications like sensing and detection [2]. The large production volume of VCSELs would benefit from a simplification of the manufacturing process flow that may largely increase the cost-effectiveness. Indeed, compared to the LED and LDs, the VCSEL fabrication process flow requires a large number of elementary steps defined by successive inter-aligned photolithography levels. A precision in the micron range is required to ensure the lateral alignment between the optical waveguide and the electrical injection. For these reasons, one of the most important concerns for the VCSEL manufacturers is to improve the production throughput by lowering the fabrication time and cost per wafer. The development of a self-aligned process is of great interest as already demonstrated for the fabrication of high performance HBT transistors or ridge lasers [3,4]. To that extent, Al-Omari [5] used a top metallic contact deposited over a photoresist layer as a hard mask to dry-etch the VCSEL mesa. Chua [6] developed a pseudo-planar approach by opening via holes down to the AlAs layer to carry out the lateral oxidation. This process has subsequently been improved by Strzelecka [7] to increase the device density. Recently, we have shown that air-post VCSELs could be created using an innovative self-aligned process, which combined several masking and lift-off steps defined by a single lithographic step [8]. In this paper, we extend this work and propose a new process flow to fabricate, in a very simple and straightforward way, the widely-used oxide-confined VCSELs. The demonstrated process drastically simplifies the oxide-confined VCSEL fabrication by reducing the total number of lithographic alignment steps from four or more to only one alignment, with the additional advantage of relieving the required tolerances. This process flow, most suitable for 3D imaging and sensing applications, can also be easily implemented for the fabrication of other optoelectronic devices such as modulators, ridge waveguide lasers, detectors, solar cells or any process combining dry etch, passivation and metallization.

Published
2017
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23. Overview of progress in European medium sized tokamaks towards an integrated plasma-edge/wall solution

Author

Eich, T., Beurskens, M., Akers, R., De Masi, G., De Temmerman, G., De Tommasi, G., Delogu, R. S., Dendy, R., Denner, P., Di Troia, C., Dimitrova, M., D’Inca, R., Dorić, V., Albanese, R., Douai, D., Drenik, A., Dudson, B., Dunai, D., Dunne, M., Duval, B. P., Easy, L., Elmore, S., Erdös, B., Esposito, B., Aledda, R., Fable, E., Faitsch, M., Fanni, A., Fedorczak, N., Felici, F., Ferreira, J., Février, O., Ficker, O., Fietz, S., Figini, L., Alessi, E., Figueiredo, A., Fil, A., Fishpool, G., Fitzgerald, M., Fontana, M., Ford, O., Frassinetti, L., Fridström, R., Frigione, D., Fuchert, G., Allan, S., Fuchs, C., Furno Palumbo, M., Futatani, S., Gabellieri, L., Gałązka, K., Galdon-Quiroga, J., Galeani, S., Gallart, D., Gallo, A., Galperti, C., Alves, D., Gao, Y., Garavaglia, S., Garcia-Carrasco, A., Garcia-Lopez, J., Garcia-Munoz, M., Gardarein, J.-L., Garzotti, L., Gaspar, J., Gauthier, E., Geelen, P., Ambrosino, R., Geiger, B., Ghendrih, P., Ghezzi, F., Giacomelli, L., Giannone, L., Giovannozzi, E., Giroud, C., Gleason González, C., Gobbin, M., Goodman, T. P., Amicucci, L., Gorini, G., Gospodarczyk, M., Granucci, G., Gruber, M., Gude, A., Guimarais, L., Guirlet, R., Gunn, J., Hacek, P., Hacquin, S., Anand, H., Ham, C., Happel, T., Harrison, J., Harting, D., Hauer, V., Havlickova, E., Hellsten, T., Helou, W., Henderson, S., Hennequin, P., Anastassiou, G., Heyn, M., Hnat, B., Hölzl, M., Hogeweij, D., Honoré, C., Hopf, C., Horáček, J., Hornung, G., Horváth, L., Huang, Z., Coda, S., Andrèbe, Y., Huber, A., Igitkhanov, J., Igochine, V., Imrisek, M., Innocente, P., Ionita-Schrittwieser, C., Isliker, H., Ivanova-Stanik, I., Jacobsen, A. S., Jacquet, P., Angioni, C., Jakubowski, M., Jardin, A., Jaulmes, F., Jenko, F., Jensen, T., Jeppe Miki Busk, O., Jessen, M., Joffrin, E., Jones, O., Jonsson, T., Apruzzese, G., Kallenbach, A., Kallinikos, N., Kálvin, S., Kappatou, A., Karhunen, J., Karpushov, A., Kasilov, S., Kasprowicz, G., Kendl, A., Kernbichler, W., Ariola, M., Kirk, A., Kjer, S., Klimek, I., Kocsis, G., Kogut, D., Komm, M., Korsholm, S. B., Koslowski, H. R., Koubiti, M., Kovacic, J., Arnichand, H., Kovarik, K., Krawczyk, N., Krbec, J., Krieger, K., Krivska, A., Kube, R., Kudlacek, O., Kurki-Suonio, T., Labit, B., Laggner, F. M., Arter, W., Laguardia, L., Lahtinen, A., Lalousis, P., Lauber, P., Lazányi, N., Lazaros, A., Le, H. B., Lebschy, A., Leddy, J., Lefévre, L., Baciero, A., Lehnen, M., Leipold, F., Lessig, A., Leyland, M., Li, L., Lipschultz, B., Liu, Y. Q., Loarer, T., Loarte, A., Loewenhoff, T., Barnes, M., Lomanowski, B., Loschiavo, V. P., Lunt, T., Lupelli, I., Lux, H., Madsen, J., Maget, P., Maggi, C., Maggiora, R., Magnussen, M. L., Barrera, L., Mailloux, J., Maljaars, B., Malygin, A., Mantica, P., Mantsinen, M., Maraschek, M., Marchand, B., Marconato, N., Marini, C., Marinucci, M., Behn, R., Markovic, T., Marocco, D., Marrelli, L., Martin, Y., Martin Solis, J. R., Martitsch, A., Mastrostefano, S., Mattei, M., Matthews, G., Mavridis, M., Hakola, A., Bencze, A., Mayoral, M.-L., Mazon, D., McCarthy, P., McAdams, R., McArdle, G., McClements, K., McDermott, R., McMillan, B., Meisl, G., Bernardo, J., Merle, A., Meyer, O., Milanesio, D., Militello, F., Miron, I. G., Mitosinkova, K., Mlynar, J., Mlynek, A., Molina, D., Molina, P., Bernert, M., Monakhov, I., Morales, J., Moreau, D., Morel, P., Moret, J.-M., Moro, A., Moulton, D., Müller, H. W., Nabais, F., Nardon, E., Bettini, P., Naulin, V., Nemes-Czopf, A., Nespoli, F., Neu, R., Nielsen, A. H., Nielsen, S. K., Nikolaeva, V., Nimb, S., Nocente, M., Nouailletas, R., Bilková, P., Nowak, S., Oberkofler, M., Oberparleiter, M., Ochoukov, R., Odstrčil, T., Olsen, J., Omotani, J., O’Mullane, M. G., Orain, F., Osterman, N., Bin, W., Paccagnella, R., Pamela, S., Pangione, L., Panjan, M., Papp, G., Papřok, R., Parail, V., Parra, F. I., Pau, A., Pautasso, G., Birkenmeier, G., Pehkonen, S.-P., Pereira, A., Perelli Cippo, E., Pericoli Ridolfini, V., Peterka, M., Petersson, P., Petrzilka, V., Piovesan, P., Piron, C., Pironti, A., Bizarro, J. P. S., Pisano, F., Pisokas, T., Pitts, R., Ploumistakis, I., Plyusnin, V., Pokol, G., Poljak, D., Pölöskei, P., Popovic, Z., Pór, G., Blanchard, P., Porte, L., Potzel, S., Predebon, I., Preynas, M., Primc, G., Pucella, G., Puiatti, M. E., Pütterich, T., Rack, M., Ramogida, G., Blanken, T., Rapson, C., Rasmussen, J. Juul, Rasmussen, J., Rattá, G. A., Ratynskaia, S., Ravera, G., Réfy, D., Reich, M., Reimerdes, H., Reimold, F., Martin, P., Bluteau, M., Reinke, M., Reiser, D., Resnik, M., Reux, C., Ripamonti, D., Rittich, D., Riva, G., Rodriguez-Ramos, M., Rohde, V., Rosato, J., Bobkov, V., Ryter, F., Saarelma, S., Sabot, R., Saint-Laurent, F., Salewski, M., Salmi, A., Samaddar, D., Sanchis-Sanchez, L., Santos, J., Sauter, O., Bogar, O., Scannell, R., Scheffer, M., Schneider, B., Schneider, P., Schneller, M., Schrittwieser, R., Schweinzer, J., Seidl, J., Sertoli, M., Šesnić, S., Böhm, P., Shabbir, A., Shalpegin, A., Shanahan, B., Sharapov, S., Sheikh, U., Sias, G., Sieglin, B., Silva, C., Silva, A., Silva Fuglister, M., Bolzonella, T., Simpson, J., Snicker, A., Sommariva, C., Sozzi, C., Spagnolo, S., Spizzo, G., Spolaore, M., Stange, T., Stejner Pedersen, M., Stepanov, I., Boncagni, L., Stober, J., Strand, P., Šušnjara, A., Suttrop, W., Szepesi, T., Tál, B., Tala, T., Tamain, P., Tardini, G., Tardocchi, M., Botrugno, A., Teplukhina, A., Terranova, D., Theiler, C., Thornton, A., Tolias, P., Tophøj, L., Treutterer, W., Trevisan, G. 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T., Walkden, N., Wang, N., Weiland, M., Weinzettl, V., Westerhof, E., Adamek, J., Brémond, S., Wiesenberger, M., Willensdorfer, M., Wischmeier, M., Wodniak, I., Wolfrum, E., Yadykin, D., Zagórski, R., Zammuto, I., Zanca, P., Zaplotnik, R., Brezinsek, S., Zestanakis, P., Zhang, W., Zoletnik, S., Zuin, M., Meyer, H., Schubert, M., Schneider, M., Wauters, T., Wagner, D., Testa, D., Brida, D., Tripsky, M., Liang, Yunfeng, Lyssoivan, A., Lang, P., Garcia, J., Hall, S., Decker, J., Kim, D., Brochard, F., Buchanan, J., Bufferand, H., Buratti, P., Cahyna, P., Calabrò, G., Camenen, Y., Agostini, M., Caniello, R., Cannas, B., Canton, A., Cardinali, A., Carnevale, D., Carr, M., Carralero, D., Carvalho, P., Casali, L., Castaldo, C., Aguiam, D., Castejón, F., Castro, R., Causa, F., Cavazzana, R., Cavedon, M., Cecconello, M., Ceccuzzi, S., Cesario, R., Challis, C. D., Chapman, I. T., Ahn, J., Chapman, S., Chernyshova, M., Choi, D., Cianfarani, C., Ciraolo, G., Citrin, J., Clairet, F., Classen, I., Coelho, R., Coenen, J. 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(FVB) (FVB), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Helmholtz-Gemeinschaft = Helmholtz Association, Institut für Experimentelle und Angewandte Physik [Kiel] (IEAP), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Politecnico di Torino = Polytechnic of Turin (Polito), Universidad de Granada = University of Granada (UGR), Swiss Plasma Center (SPC), Meyer, H., Eich, T., Beurskens, M., Coda, S., Hakola, A., Martin, P., Adamek, J., Agostini, M., Aguiam, D., Ahn, J., Aho-Mantila, L., Akers, R., Albanese, R., Aledda, R., Alessi, E., Allan, S., Alves, D., Ambrosino, R., Amicucci, L., Anand, H., Anastassiou, G., Andrèbe, Y., Angioni, C., Apruzzese, G., Ariola, M., Arnichand, H., Arter, W., Baciero, A., Barnes, M., Barrera, L., Behn, R., Bencze, A., Bernardo, J., Bernert, M., Bettini, P., Bilková, P., Bin, W., Birkenmeier, G., Bizarro, J. P. S., Blanchard, P., Blanken, T., Bluteau, M., Bobkov, V., Bogar, O., Böhm, P., Bolzonella, T., Boncagni, L., Botrugno, A., Bottereau, C., Bouquey, F., Bourdelle, C., Brémond, S., Brezinsek, S., Brida, D., Brochard, F., Buchanan, J., Bufferand, H., Buratti, P., Cahyna, P., Calabrò, G., Camenen, Y., Caniello, R., Cannas, B., Canton, A., Cardinali, A., Carnevale, D., Carr, M., Carralero, D., Carvalho, P., Casali, L., Castaldo, C., Castejón, F., Castro, R., Causa, F., Cavazzana, R., Cavedon, M., Cecconello, M., Ceccuzzi, S., Cesario, R., Challis, C. D., Chapman, I. T., Chapman, S., Chernyshova, M., Choi, D., Cianfarani, C., Ciraolo, G., Citrin, J., Clairet, F., Classen, I., Coelho, R., Coenen, J. W., Colas, L., Conway, G., Corre, Y., Costea, S., Crisanti, F., Cruz, N., Cseh, G., Czarnecka, A., D’Arcangelo, O., De Angeli, M., De Masi, G., De Temmerman, G., De Tommasi, G., Decker, J., Delogu, R. S., Dendy, R., Denner, P., Di Troia, C., Dimitrova, M., D’Inca, R., Dorić, V., Douai, D., Drenik, A., Dudson, B., Dunai, D., Dunne, M., Duval, B. P., Easy, L., Elmore, S., Erdös, B., Esposito, B., Fable, E., Faitsch, M., Fanni, A., Fedorczak, N., Felici, F., Ferreira, J., Février, O., Ficker, O., Fietz, S., Figini, L., Figueiredo, A., Fil, A., Fishpool, G., Fitzgerald, M., Fontana, M., Ford, O., Frassinetti, L., Fridström, R., Frigione, D., Fuchert, G., Fuchs, C., Furno Palumbo, M., Futatani, S., Gabellieri, L., Gałązka, K., Galdon-Quiroga, J., Galeani, S., Gallart, D., Gallo, A., Galperti, C., Gao, Y., Garavaglia, S., Garcia, J., Garcia-Carrasco, A., Garcia-Lopez, J., Garcia-Munoz, M., Gardarein, J. -L., Garzotti, L., Gaspar, J., Gauthier, E., Geelen, P., Geiger, B., Ghendrih, P., Ghezzi, F., Giacomelli, L., Giannone, L., Giovannozzi, E., Giroud, C., Gleason González, C., Gobbin, M., Goodman, T. P., Gorini, G., Gospodarczyk, M., Granucci, G., Gruber, M., Gude, A., Guimarais, L., Guirlet, R., Gunn, J., Hacek, P., Hacquin, S., Hall, S., Ham, C., Happel, T., Harrison, J., Harting, D., Hauer, V., Havlickova, E., Hellsten, T., Helou, W., Henderson, S., Hennequin, P., Heyn, M., Hnat, B., Hölzl, M., Hogeweij, D., Honoré, C., Hopf, C., Horáček, J., Hornung, G., Horváth, L., Huang, Z., Huber, A., Igitkhanov, J., Igochine, V., Imrisek, M., Innocente, P., Ionita-Schrittwieser, C., Isliker, H., Ivanova-Stanik, I., Jacobsen, A. S., Jacquet, P., Jakubowski, M., Jardin, A., Jaulmes, F., Jenko, F., Jensen, T., Jeppe Miki Busk, O., Jessen, M., Joffrin, E., Jones, O., Jonsson, T., Kallenbach, A., Kallinikos, N., Kálvin, S., Kappatou, A., Karhunen, J., Karpushov, A., Kasilov, S., Kasprowicz, G., Kendl, A., Kernbichler, W., Kim, D., Kirk, A., Kjer, S., Klimek, I., Kocsis, G., Kogut, D., Komm, M., Korsholm, S. B., Koslowski, H. R., Koubiti, M., Kovacic, J., Kovarik, K., Krawczyk, N., Krbec, J., Krieger, K., Krivska, A., Kube, R., Kudlacek, O., Kurki-Suonio, T., Labit, B., Laggner, F. M., Laguardia, L., Lahtinen, A., Lalousis, P., Lang, P., Lauber, P., Lazányi, N., Lazaros, A., Le, H. B., Lebschy, A., Leddy, J., Lefévre, L., Lehnen, M., Leipold, F., Lessig, A., Leyland, M., Li, L., Liang, Y., Lipschultz, B., Liu, Y. Q., Loarer, T., Loarte, A., Loewenhoff, T., Lomanowski, B., Loschiavo, V. P., Lunt, T., Lupelli, I., Lux, H., Lyssoivan, A., Madsen, J., Maget, P., Maggi, C., Maggiora, R., Magnussen, M. L., Mailloux, J., Maljaars, B., Malygin, A., Mantica, P., Mantsinen, M., Maraschek, M., Marchand, B., Marconato, N., Marini, C., Marinucci, M., Markovic, T., Marocco, D., Marrelli, L., Martin, Y., Martin Solis, J. 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I., Pau, A., Pautasso, G., Pehkonen, S. -P., Pereira, A., Perelli Cippo, E., Pericoli Ridolfini, V., Peterka, M., Petersson, P., Petrzilka, V., Piovesan, P., Piron, C., Pironti, A., Pisano, F., Pisokas, T., Pitts, R., Ploumistakis, I., Plyusnin, V., Pokol, G., Poljak, D., Pölöskei, P., Popovic, Z., Pór, G., Porte, L., Potzel, S., Predebon, I., Preynas, M., Primc, G., Pucella, G., Puiatti, M. E., Pütterich, T., Rack, M., Ramogida, G., Rapson, C., Rasmussen, J. Juul, Rasmussen, J., Rattá, G. A., Ratynskaia, S., Ravera, G., Réfy, D., Reich, M., Reimerdes, H., Reimold, F., Reinke, M., Reiser, D., Resnik, M., Reux, C., Ripamonti, D., Rittich, D., Riva, G., Rodriguez-Ramos, M., Rohde, V., Rosato, J., Ryter, F., Saarelma, S., Sabot, R., Saint-Laurent, F., Salewski, M., Salmi, A., Samaddar, D., Sanchis-Sanchez, L., Santos, J., Sauter, O., Scannell, R., Scheffer, M., Schneider, M., Schneider, B., Schneider, P., Schneller, M., Schrittwieser, R., Schubert, M., Schweinzer, J., Seidl, J., Sertoli, M., Šesnić, S., Shabbir, A., Shalpegin, A., Shanahan, B., Sharapov, S., Sheikh, U., Sias, G., Sieglin, B., Silva, C., Silva, A., Silva Fuglister, M., Simpson, J., Snicker, A., Sommariva, C., Sozzi, C., Spagnolo, S., Spizzo, G., Spolaore, M., Stange, T., Stejner Pedersen, M., Stepanov, I., Stober, J., Strand, P., Šušnjara, A., Suttrop, W., Szepesi, T., Tál, B., Tala, T., Tamain, P., Tardini, G., Tardocchi, M., Teplukhina, A., Terranova, D., Testa, D., Theiler, C., Thornton, A., Tolias, P., Tophøj, L., Treutterer, W., Trevisan, G. 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T., Wagner, D., Walkden, N., Wang, N., Wauters, T., Weiland, M., Weinzettl, V., Westerhof, E., Wiesenberger, M., Willensdorfer, M., Wischmeier, M., Wodniak, I., Wolfrum, E., Yadykin, D., Zagórski, R., Zammuto, I., Zanca, P., Zaplotnik, R., Zestanakis, P., Zhang, W., Zoletnik, S., Zuin, M., Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Meyer, H, Eich, T, Beurskens, M, Coda, S, Hakola, A, Martin, P, Adamek, J, Agostini, M, Aguiam, D, Ahn, J, Aho-Mantila, L, Akers, R, Albanese, R, Aledda, R, Alessi, E, Allan, S, Alves, D, Ambrosino, R, Amicucci, L, Anand, H, Anastassiou, G, Andrãbe, Y, Angioni, C, Apruzzese, G, Ariola, M, Arnichand, H, Arter, W, Baciero, A, Barnes, M, Barrera, L, Behn, R, Bencze, A, Bernardo, J, Bernert, M, Bettini, P, Bilkovã¡, P, Bin, W, Birkenmeier, G, Bizarro, J, Blanchard, P, Blanken, T, Bluteau, M, Bobkov, V, Bogar, O, Bã¶hm, P, Bolzonella, T, Boncagni, L, Botrugno, A, Bottereau, C, Bouquey, F, Bourdelle, C, Brã©mond, S, Brezinsek, S, Brida, D, Brochard, F, Buchanan, J, Bufferand, H, Buratti, P, Cahyna, P, Calabrã², G, Camenen, Y, Caniello, R, Cannas, B, Canton, A, Cardinali, A, Carnevale, D, Carr, M, Carralero, D, Carvalho, P, Casali, L, Castaldo, C, Castejã³n, F, Castro, R, Causa, F, Cavazzana, R, Cavedon, M, Cecconello, M, Ceccuzzi, S, Cesario, R, Challis, C, Chapman, I, Chapman, S, Chernyshova, M, Choi, D, Cianfarani, C, Ciraolo, G, Citrin, J, Clairet, F, Classen, I, Coelho, R, Coenen, J, Colas, L, Conway, G, Corre, Y, Costea, S, Crisanti, F, Cruz, N, Cseh, G, Czarnecka, A, D'Arcangelo, O, De Angeli, M, De Masi, G, De Temmerman, G, De Tommasi, G, Decker, J, Delogu, R, Dendy, R, Denner, P, Di Troia, C, Dimitrova, M, D'Inca, R, Dorić, V, Douai, D, Drenik, A, Dudson, B, Dunai, D, Dunne, M, Duval, B, Easy, L, Elmore, S, Erdã¶s, B, Esposito, B, Fable, E, Faitsch, M, Fanni, A, Fedorczak, N, Felici, F, Ferreira, J, Fã©vrier, O, Ficker, O, Fietz, S, Figini, L, Figueiredo, A, Fil, A, Fishpool, G, Fitzgerald, M, Fontana, M, Ford, O, Frassinetti, L, Fridstrã¶m, R, Frigione, D, Fuchert, G, Fuchs, C, Furno Palumbo, M, Futatani, S, Gabellieri, L, GaÅ‚azka, K, Galdon-Quiroga, J, Galeani, S, Gallart, D, Gallo, A, Galperti, C, Gao, Y, Garavaglia, S, Garcia, J, Garcia-Carrasco, A, Garcia-Lopez, J, Garcia-Munoz, M, Gardarein, J, Garzotti, L, Gaspar, J, Gauthier, E, Geelen, P, Geiger, B, Ghendrih, P, 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Haute-Alsace (UHA) ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ) -Centre National de la Recherche Scientifique ( CNRS ) -Réseau nanophotonique et optique, Université de Strasbourg ( UNISTRA ) -Université de Haute-Alsace (UHA) Mulhouse - Colmar ( Université de Haute-Alsace (UHA) ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Strasbourg ( UNISTRA ), Max-Planck-Institut für Plasmaphysik [Garching] ( IPP ), Culham Science Centre, Institute of Plasma Physics, Association Euratom/IPP.CR ( IPP PRAGUE ), Czech Academy of Sciences [Prague] ( ASCR ), VTT Technical Research Centre of Finland ( VTT ), Univ. Mediterranea RC, Universidad Metropolitana de Ciencias de la Educación ( UMCE ), Laboratoire de Biométrie et Biologie Evolutive ( LBBE ), Université Claude Bernard Lyon 1 ( UCBL ), Université de Lyon-Université de Lyon-Institut National de Recherche en Informatique et en Automatique ( Inria ) -Centre National de la Recherche Scientifique ( CNRS ), Institut de Recherche sur la Fusion par confinement Magnétique ( IRFM ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ), Institute of Energy and Climate Research - Plasma Physics ( IEK-4 ), Laboratoire Leprince-Ringuet ( LLR ), Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -École polytechnique ( X ) -Centre National de la Recherche Scientifique ( CNRS ), Physique des interactions ioniques et moléculaires ( PIIM ), Aix Marseille Université ( AMU ) -Centre National de la Recherche Scientifique ( CNRS ), Institut des Sciences et Ingénierie Chimiques ( ISIC ), Ecole Polytechnique Fédérale de Lausanne ( EPFL ), Institute of Plasma Physics and Laser Microfusion [Warsaw] ( IPPLM ), Instituto de Plasmas e Fusão Nuclear [Lisboa] ( IPFN ), Instituto Superior Técnico, Universidade Técnica de Lisboa ( IST ), University of Basel ( Unibas ), Ferdinand-Braun-Institut für Höchtstfrequenztechnik ( FBH ), Institut de biologie moléculaire des plantes ( IBMP ), Université de Strasbourg ( UNISTRA ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de glaciologie et géophysique de l'environnement ( LGGE ), Observatoire des Sciences de l'Univers de Grenoble ( OSUG ), Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ) -Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ) -Centre National de la Recherche Scientifique ( CNRS ), Génétique du cancer et des maladies neuropsychiatriques ( GMFC ), Université de Rouen Normandie ( UNIROUEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ), Institute of Geophysics and Planetary Physics, Department of Physics, Stockholm University ( Department of Physics, Stockholm University ), Université de Lille, Sciences Humaines et Sociales, Département Recherches Subatomiques ( DRS-IPHC ), Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique ( CNRS ), Key Laboratory of Molecular Virology & Immunology ( LMVI ), Réseau International des Instituts Pasteur ( RIIP ) -Institut Pasteur de Shanghai - Académie des Sciences de Chine, Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Université de Franche-Comté ( UFC ) -Centre National de la Recherche Scientifique ( CNRS ), Christian-Albrechts-Universität zu Kiel ( CAU ), Laboratoire de Physique des Plasmas ( LPP ), Université Paris-Sud - Paris 11 ( UP11 ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Observatoire de Paris-École polytechnique ( X ) -Sorbonne Universités-PSL Research University ( PSL ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Space and Astrophysics, Institute of Plasma Physics, Association EURATOM ( IPP PRAGUE ), Univ. Grenoble Alpes, LCIS, York Plasma Institute ( YPI ), University of Wisconsin-Madison [Madison], Association EURATOM-CEA ( CEA/DSM/DRFC ), Euratom/UKEAE Fusion Association ( JET ), European Synchrotron Radiation Facility ( ESRF ), Politecnico di Torino [Torino] ( Polito ), Instituto Andaluz de Geofísica, Universidad de Granada, Université du Québec, Etablissement français du sang [Besançon] ( EFS ), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Recherche pour le Développement (IRD)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), D'Arcangelo, O., Max Planck Institute for Plasma Physics, Swiss Federal Institute of Technology Lausanne, VTT Technical Research Centre of Finland, National Research Council of Italy, Czech Academy of Sciences, Instituto Superior Tecnico Lisboa, CEA, University of Naples Federico II, University of Cagliari, University of Naples Parthenope, Agenzia nazionale per le nuove tecnologie, l'energia e lo sviluppo economico sostenibile, National Technical University of Athens, CIEMAT, University of Oxford, EUROfusion Programme Management Unit, Wigner Research Centre for Physics, University of Strathclyde, Jülich Research Centre, Université de Lorraine, CNRS, University of Rome Tor Vergata, Uppsala University, University of Warwick, Soltan Institute for Nuclear Studies, Dutch Institute for Fundamental Energy Research, University of Innsbruck, University of Split, University of York, Budapest University of Technology and Economics, KTH Royal Institute of Technology, Barcelona Supercomputing Center, University of Seville, Karlsruhe Institute of Technology, University of Milan - Bicocca, Université Paris-Sud, Graz University of Technology, Royal Military Academy, Ghent University, Aristotle University of Thessaloniki, Technical University of Denmark, Department of Applied Physics, Vienna University of Technology, University of Helsinki, Foundation for Research and Technology-Hellas, Université Grenoble Alpes, Forschungszentrum Jülich, Durham University, Polytechnic University of Turin, University of Cassino and Southern Lazio, University College Cork, National Institute for Laser, Plasma and Radiation Physics, Chalmers University of Technology, Aalto-yliopisto, Aalto University, Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. ANT - Advanced Nuclear Technologies Research Group, Andrãbe, Y., Bilkovã¡, P., Bã¶hm, P., Brã©mond, S., Calabrã², G., Castejã³n, F., D'Inca, R., Doriä , V., Erdã¶s, B., Fã©vrier, O., Fridstrã¶m, R., Gaå azka, K., Gardarein, J. -. L., Gleason González, C., Hã¶lzl, M., Honorã©, C., Horã¡ä ek, J., Horvã¡th, L., Kã¡lvin, S., Lazã¡nyi, N., Lefã©vre, L., Mayoral, M. -. L., Moret, J. -. M., Mã¼ller, H. W., Odsträ il, T., O'Mullane, M. G., Papå ok, R., Pehkonen, S. -. P., Pã¶lã¶skei, P., Pã³r, G., Pã¼tterich, T., Rattã¡, G. A., Rã©fy, D., Å esniä , S., Å uå¡njara, A., Tã¡l, B., Tophj, L., Van Den Brand, H., Vondrã¡ä ek, P., Zagã³rski, R., and Department of Physics

Subjects
Tokamak, Asdex upgrade, 01 natural sciences, 010305 fluids & plasmas, law.invention, heat loads, Divertor, ASDEX Upgrade, ASDEX upgrade, law, Fusió nuclear, Magnetoplasma, ComputingMilieux_MISCELLANEOUS, Physics, [SPI.PLASMA]Engineering Sciences [physics]/Plasmas, Plasma turbulence, alternative divertor concept, Condensed Matter Physics, Fusion, Plasma and Space Physics, edge localised mode, Thermal load, edge localised modes, Localised, TCV, [ SPI.PLASMA ] Engineering Sciences [physics]/Plasmas, PARTICLE, divertor, MAST, alternative divertor concepts, Nuclear and High Energy Physics, Materials science, Plasma (Gasos ionitzats), 114 Physical sciences, [SPI.AUTO]Engineering Sciences [physics]/Automatic, Fusion, plasma och rymdfysik, Fusion reactor divertors, Settore ING-INF/04 - Automatica, [ SPI.AUTO ] Engineering Sciences [physics]/Automatic, 0103 physical sciences, heat load, ddc:530, Aerospace engineering, 010306 general physics, Nuclear and High Energy Physic, Plasma (Ionized gases), Física [Àrees temàtiques de la UPC], business.industry, Mast, Física, Nuclear energy, Plasma, SCRAPE-OFF LAYER, Plasma edge, Alternative divertor concepts, DENSITY, Sols, Nuclear fusion, Energia nuclear, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Integrating the plasma core performance with an edge and scrape-off layer (SOL) that leads to tolerable heat and particle loads on the wall is a major challenge. The new European medium size tokamak task force (EU-MST) coordinates research on ASDEX Upgrade (AUG), MAST and TCV. This multi-machine approach within EU-MST, covering a wide parameter range, is instrumental to progress in the field, as ITER and DEMO core/pedestal and SOL parameters are not achievable simultaneously in present day devices. A two prong approach is adopted. On the one hand, scenarios with tolerable transient heat and particle loads, including active edge localised mode (ELM) control are developed. On the other hand, divertor solutions including advanced magnetic configurations are studied. Considerable progress has been made on both approaches, in particular in the fields of: ELM control with resonant magnetic perturbations (RMP), small ELM regimes, detachment onset and control, as well as filamentary scrape-off-layer transport. For example full ELM suppression has now been achieved on AUG at low collisionality with n = 2 RMP maintaining good confinement HH(98,y2)≈0.95. Advances have been made with respect to detachment onset and control. Studies in advanced divertor configurations (Snowflake, Super-X and X-point target divertor) shed new light on SOL physics. Cross field filamentary transport has been characterised in a wide parameter regime on AUG, MAST and TCV progressing the theoretical and experimental understanding crucial for predicting first wall loads in ITER and DEMO. Conditions in the SOL also play a crucial role for ELM stability and access to small ELM regimes. Integrating the plasma core performance with an edge and scrape-off layer (SOL) that leads to tolerable heat and particle loads on the wall is a major challenge. The new European medium size tokamak task force (EU-MST) coordinates research on ASDEX Upgrade (AUG), MAST and TCV. This multi-machine approach within EU-MST, covering a wide parameter range, is instrumental to progress in the field, as ITER and DEMO core/pedestal and SOL parameters are not achievable simultaneously in present day devices. A two prong approach is adopted. On the one hand, scenarios with tolerable transient heat and particle loads, including active edge localised mode (ELM) control are developed. On the other hand, divertor solutions including advanced magnetic configurations are studied. Considerable progress has been made on both approaches, in particular in the fields of: ELM control with resonant magnetic perturbations (RMP), small ELM regimes, detachment onset and control, as well as filamentary scrape-off-layer transport. For example full ELM suppression has now been achieved on AUG at low collisionality with n = 2 RMP maintaining good confinement H-H(98,H-y2) approximate to 0.95. Advances have been made with respect to detachment onset and control. Studies in advanced divertor configurations (Snowflake, Super-X and X-point target divertor) shed new light on SOL physics. Cross field filamentary transport has been characterised in a wide parameter regime on AUG, MAST and TCV progressing the theoretical and experimental understanding crucial for predicting first wall loads in ITER and DEMO. Conditions in the SOL also play a crucial role for ELM stability and access to small ELM regimes.

Published
2017
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24. Injection locking and polarization switching bistability in a 1550 nm VCSEL subject to parallel optical injection

Author

Pablo Pérez, Florian Denis-le Coarer, Marc Sciamanna, Hugo Thienpont, Luis Pesquera, Angel Valle, Ana Quirce, Krassimir Panajotov, Applied Physics and Photonics, Brussels Photonics Team, Laboratoire matériaux organiques à propriétés spécifiques ( LMOPS ), Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces ( LEPMI ), Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut National Polytechnique de Grenoble ( INPG ) -Université Savoie Mont Blanc ( USMB [Université de Savoie] [Université de Chambéry] ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut National Polytechnique de Grenoble ( INPG ) -Université Savoie Mont Blanc ( USMB [Université de Savoie] [Université de Chambéry] ) -Centre National de la Recherche Scientifique ( CNRS ), Chaire Photonique, Laboratoire Matériaux Optiques, Photonique et Systèmes ( LMOPS ), CentraleSupélec-Université de Lorraine ( UL ) -CentraleSupélec-Université de Lorraine ( UL ), Centro de estudios e investigaciones laborales del Consejo Nacional de Investigaciones Cientificas y Tecnologicas de Argentina ( CEIL-PIETTE DEL CONICET ), Universidad de Buenos Aires [Buenos Aires], Instituto de Fisica de Cantabria ( IFCA ), Universidad de Cantabria [Santander]-Consejo Superior de Investigaciones Científicas [Spain] ( CSIC ), Instituto de Física de Cantabria ( CSIC-UC ), Instituto de Física de Cantabria, CentraleSupélec-Université de Lorraine ( UL ), Department of Applied Physics and Photonics [Brussels] ( TONA ), Vrije Universiteit [Brussel] ( VUB ), Laboratoire Matériaux Optiques, Photonique et Systèmes (LMOPS), CentraleSupélec-Université de Lorraine (UL)-CentraleSupélec-Université de Lorraine (UL), CentraleSupélec-Université de Lorraine (UL), Centro de estudios e investigaciones laborales [Buenos Aires] (CEIL), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET), Instituto de Fisica de Cantabria (IFCA), Universidad de Cantabria [Santander]-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Instituto de Física de Cantabria (IFCA), Department of Applied Physics and Photonics [Brussels] (TONA), and Vrije Universiteit Brussel (VUB)

Subjects
VCSELs, Materials science, Bistability, bistability, Optical bistability, 02 engineering and technology, Laser mode locking, Semiconductor laser theory, Vertical-cavity surface-emitting laser, [SPI]Engineering Sciences [physics], 020210 optoelectronics & photonics, 0202 electrical engineering, electronic engineering, information engineering, [ SPI ] Engineering Sciences [physics], [NLIN]Nonlinear Sciences [physics], Electrical and Electronic Engineering, [PHYS]Physics [physics], Semiconductor lasers, [ PHYS ] Physics [physics], business.industry, Orthogonal polarization spectral imaging, [ NLIN ] Nonlinear Sciences [physics], Optical polarization, injection-locked lasers, Optical coupling, Atomic and Molecular Physics, and Optics, Transverse mode, Injection locking, Optoelectronics, business, Optical attenuators, vertical-cavity surface-emitting lasers
Abstract

We present experimental and theoretical results of bistable polarization switching in a single transverse mode 1550 nm vertical-cavity surface-emitting laser (VCSEL) subject to parallel optical injection. We focus our analysis on the bistability induced by power variation of the master laser found on the recently observed state of simultaneous injection locking of the parallel polarization mode and excitation of the orthogonal polarization mode, IL+PS. Experimental stability maps identifying, in the injected power-frequency detuning plane, where this state is observed, and corresponding bistable regions are reported for several bias currents. We find bistability between the IL+PS state and the single polarization mode injection locked solution. We also find bistability between the IL+PS and different periodic dynamics in the parallel polarization mode. The width of the hysteresis cycle increases when increasing the bias current or when increasing the wavelength of the optical injection beyond the solitary VCSEL wavelength. We theoretically confirm these types of bistability by numerically simulating the spin-flip model and by performing a linear stability analysis for the different stable states. Excellent agreement is found between experimental and theoretical results.

Published
2017
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25. Wavelength switching speed in semiconductor ring lasers with on-chip filtered optical feedback

Author

Jan Danckaert, Guy Verschaffelt, Xaveer Leijtens, Romain Modeste Nguimdo, Mulham Khoder, Jeroen Bolk, Savory, Seb J., Applied Physics, Physics, Applied Physics and Photonics, Photonic Integration, and NanoLab@TU/e

Subjects
Optical amplifier, Materials science, business.industry, Filtered feedback, Photonic integrated circuit, tunable lasers, Physics::Optics, Semiconductor ring laser, Optical burst switching, Optical switch, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Semiconductor laser theory, Switching time, Wavelength, Optics, Optoelectronics, packet switching, Electrical and Electronic Engineering, business, semiconductor ring lasers
Abstract

We experimentally and numerically characterize the wavelength switching speed of a tunable semiconductor ring laser using filtered optical feedback. The feedback is realized employing two arrayed-waveguide gratings to split/recombine light into different wavelength channels. The wavelength tuning and switching is controlled by changing the currents injected in semiconductor optical amplifiers in the feedback section. A wavelength switching speed of a few nanoseconds is achieved. We investigate also the effect of the feedback parameters and noise strength on the wavelength switching speed.

Published
2014
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26. Detection of OH in an atmospheric flame at 1.5 um using optical frequency comb spectroscopy

Author

Amir Khodabakhsh, Aleksandra Foltynowicz, Arkadiusz Tkacz, Florian M. Schmidt, Damir Valiev, Lucile Rutkowski, Alexandra C. Johansson, Department of Physics [Umeå], Umeå University, Thermochemical Energy Conversion Laboratory, Department of Applied Physics and Electronics [Umeå]], Military University of Technology, Institute of Optoelectronics, and Thermochemical Energy Conversion Laboratory, Department of Applied Physics and Electronics [Umeå]

Subjects
Materials science, 010504 meteorology & atmospheric sciences, Absorption spectroscopy, Optical frequency comb spectroscopy, 01 natural sciences, law.invention, 010309 optics, symbols.namesake, Optics, law, 0103 physical sciences, Broadband, Fiber, Spectroscopy, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [PHYS]Physics [physics], Atmospheric pressure, business.industry, Laser, Electronic, Optical and Magnetic Materials, Fourier transform, 13. Climate action, Femtosecond, symbols, business, Molecular physics
Abstract

We report broadband detection of OH in a premixed CH4/air flat flame at atmospheric pressure using cavity-enhanced absorption spectroscopy based on an Er:fiber femtosecond laserand a Fourier transform spectrometer.By taking ratios of spectra measured at different heights above the burner we separate twenty OH transitions from the largely overlapping water background. Weretrieve from fits to the OH lines the relative variation of the OH concentration and flame temperature with height above the burner and compare them with 1-D simulations of the flamestructure. Full Text: PDF ReferencesG. Meijer, M. G. Boogaarts, R. T. Jongma, D. H. Parker and A. M. Wodtke, "Coherent cavity ring down spectroscopy", Chem. Phys. Lett. 217, 1, 112 (1994). CrossRef S. Cheskis, I. Derzy, V. A. Lozovsky, A. Kachanov and D. Romanini, "Cavity ring-down spectroscopy of OH radicals in low pressure flame", Appl. Phys. B 66, 3, 377 (1998). CrossRef X. Mercier, E. Therssen, J. F. Pauwels and P. Desgroux, "Cavity ring-down measurements of OH radical in atmospheric premixed and diffusion flames.: A comparison with laser-induced fluorescence and direct laser absorption", Chem. Phys. Lett. 299, 1, 75 (1999). CrossRef J. Scherer, D. Voelkel and D. Rakestraw, "Infrared cavity ringdown laser absorption spectroscopy (IR-CRLAS) in low pressure flames", Appl. Phys. B 64, 6, 699 (1997). CrossRef R. Peeters, G. Berden and G. Meijer, "Near-infrared cavity enhanced absorption spectroscopy of hot water and OH in an oven and in flames", Appl. Phys. B 73, 1, 65 (2001). CrossRef T. Aizawa, "Diode-laser wavelength-modulation absorption spectroscopy for quantitative in situ measurements of temperature and OH radical concentration in combustion gases", Appl. Opt. 40, 27, 4894 (2001). CrossRef B. Löhden, S. Kuznetsova, K. Sengstock, V. M. Baev, et al., "Fiber laser intracavity absorption spectroscopy for in situ multicomponent gas analysis in the atmosphere and combustion environments", Appl. Phys. B 102, 2, 331 (2011). CrossRef A. Matynia, M. Idir, J. Molet, C. Roche, et al., "Absolute OH concentration profiles measurements in high pressure counterflow flames by coupling LIF, PLIF, and absorption techniques", Appl. Phys. B 108, 2, 393 (2012). CrossRef R. S. Watt, T. Laurila, C. F. Kaminski and J. Hult, "Cavity Enhanced Spectroscopy of High-Temperature H2O in the Near-Infrared Using a Supercontinuum Light Source", Appl. Spectrosc. 63, 12, 1389 (2009). CrossRef C. Abd Alrahman, A. Khodabakhsh, F. M. Schmidt, Z. Qu and A. Foltynowicz, "Cavity-enhanced optical frequency comb spectroscopy of high-temperature H2O in a flame", Opt. Express 22, 11, 13889 (2014). CrossRef A. Foltynowicz, P. Maslowski, A. J. Fleisher, B. J. Bjork and J. Ye, "Cavity-enhanced optical frequency comb spectroscopy in the mid-infrared application to trace detection of hydrogen peroxide", Appl. Phys. B 110, 2, 163 (2013). CrossRef Z. Qu, R. Ghorbani, D. Valiev and F. M. Schmidt, "Calibration-free scanned wavelength modulation spectroscopy ? application to H2O and temperature sensing in flames", Opt. Express 23, 12, 16492 (2015). CrossRef L. Rutkowski, A. Khodabakhsh, A. C. Johansson, D. M. Valiev, et al., "Measurement of H2O and OH in a Flame by Optical Frequency Comb Spectroscopy", CLEO: Science and Innovations SW4H.8 (2016). CrossRef L. S. Rothman, I. E. Gordon, Y. Babikov, A. Barbe, et al., "The HITRAN2012 molecular spectroscopic database", J. Quant. Spectrosc. Radiat. Transf. 130, 4 (2013). CrossRef

Published
2016
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27. Status and prospects for atomic layer deposited metal oxide thin films in passivating contacts for c-Si photovoltaics

Author

W. M. M. Erwin Kessels, Bart Macco, Bas W. H. van de Loo, Jimmy Melskens, Sjoerd Smit, Plasma & Materials Processing, Applied Physics and Science Education, Atomic scale processing, Processing of low-dimensional nanomaterials, and Applied Physics

Subjects
010302 applied physics, Materials science, carrier selectivity, Passivation, business.industry, transparent conductive oxides, Heterojunction, Nanotechnology, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Metal oxide thin films, Atomic layer deposition, passivating contacts, Photovoltaics, 0103 physical sciences, atomic layer deposition, SDG 7 - Affordable and Clean Energy, passivation, Homojunction, 0210 nano-technology, business, silicon heterojunctions, Layer (electronics), Transparent conducting film
Abstract

In the field of photovoltaics, atomic layer deposition (ALD) is mostly known for its success in preparing Al2O3-based surface passivation layers for c-Si homojunction cells. In the last years, many novel types of c-Si heterojunctions have appeared, referred to as passivating contacts. In these concepts, metal oxide thin films are used for surface passivation, carrier selectivity and as transparent conductive oxide. This leads to the question whether the success of ALD for homojunctions can be translated into this new field as well. Therefore, this work provides an overview of these new concepts, and highlights both the current role and prospects of ALD in this field.

Published
2016

28. Subfemtonewton Force Spectroscopy at the Thermal Limit in Liquids

Author

Federico Capasso, Vincent Ginis, Lulu Liu, Simon Kheifets, Applied Physics and Photonics, Applied Physics, and Physics

Subjects
Materials science, business.industry, Mie scattering, Resolution (electron density), Force spectroscopy, FOS: Physical sciences, General Physics and Astronomy, Physics::Optics, 02 engineering and technology, Dielectric, 021001 nanoscience & nanotechnology, Tracking (particle physics), 01 natural sciences, Displacement (vector), Optics, 0103 physical sciences, Particle, Thermal limit, 010306 general physics, 0210 nano-technology, business, Optics (physics.optics), Physics - Optics
Abstract

We demonstrate thermally limited force spectroscopy using a probe formed by a dielectric microsphere optically trapped in water near a dielectric surface. We achieve force resolution below 1 fN in 100 s, corresponding to a 2 {\AA} rms displacement of the probe. Our measurement combines a calibrated evanescent wave particle tracking technique and a lock-in detection method. We demonstrate the accuracy of our method by measurement of the height-dependent force exerted on the probe by an evanescent wave, the results of which are in agreement with Mie theory calculations., Comment: 5 pages; 4 figures

Published
2016

29. Reducing the sensitivity of semiconductor ring lasers to external optical injection using selective optical feedback

Author

Guy Verschaffelt, Guy Van der Sande, Mulham Khoder, Faculty of Engineering, Applied Physics and Photonics, and Applied Physics

Subjects
Materials science, business.industry, Physics::Optics, General Physics and Astronomy, 02 engineering and technology, Semiconductor ring laser, Physics and Astronomy(all), Laser, Ring (chemistry), Noise (electronics), law.invention, Wavelength, 020210 optoelectronics & photonics, Semiconductor, law, 0202 electrical engineering, electronic engineering, information engineering, Optoelectronics, Sensitivity (control systems), business, Bifurcation, MODULATION BANDWIDTH, THEORETICAL-ANALYSIS, LOCKING, SUBJECT, BIFURCATION, GENERATION, STABILITY, DYNAMICS, MODES, NOISE
Abstract

We numerically investigate the influence of an integrated filtered optical feedback on the behavior of a semiconductor ring laser subject to external optical injection. The optical injection is spectrally directed at one of the non-lasing longitudinal modes of the laser. This so-called side-mode injection can cause wavelength switching, directional switching, and changes in the dynamical regime of the semiconductor ring laser. Such changes are often unwanted as they can affect the stability and the performance of the semiconductor ring laser. We investigate to what extent these undesired effects can be avoided by stabilizing the laser using on-chip filtered feedback. A two-directional mode model is used to investigate the dynamical behavior of the semiconductor ring laser under the simultaneous effect of the external optical injection and the integrated feedback. The results show that on-chip filtered optical feedback can be used to reduce the sensitivity of the semiconductor ring laser to external optical injection.We numerically investigate the influence of an integrated filtered optical feedback on the behavior of a semiconductor ring laser subject to external optical injection. The optical injection is spectrally directed at one of the non-lasing longitudinal modes of the laser. This so-called side-mode injection can cause wavelength switching, directional switching, and changes in the dynamical regime of the semiconductor ring laser. Such changes are often unwanted as they can affect the stability and the performance of the semiconductor ring laser. We investigate to what extent these undesired effects can be avoided by stabilizing the laser using on-chip filtered feedback. A two-directional mode model is used to investigate the dynamical behavior of the semiconductor ring laser under the simultaneous effect of the external optical injection and the integrated feedback. The results show that on-chip filtered optical feedback can be used to reduce the sensitivity of the semiconductor ring laser to external optica...

Published
2018
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30. Vertical electro-absorption modulator design and its integration in a VCSEL

Author

Stephane Calvez, Krassimir Panajotov, Hugo Thienpont, Guilhem Almuneau, Alexandre Arnoult, Ludovic Marigo-Lombart, Équipe Photonique (LAAS-PHOTO), Laboratoire d'analyse et d'architecture des systèmes (LAAS), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées, Service Techniques et Équipements Appliqués à la Microélectronique (LAAS-TEAM), Department of Applied Physics and Photonics [Brussels] (TONA), Vrije Universiteit Brussel (VUB), Applied Physics and Photonics, Faculty of Engineering, Brussels Photonics Team, Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse Capitole (UT Capitole), and Université de Toulouse (UT)

Subjects
Materials science, Acoustics and Ultrasonics, Optical communication, Physics::Optics, 02 engineering and technology, VCSEL, Vertical-cavity surface-emitting laser, law.invention, 020210 optoelectronics & photonics, law, Electro-absorption modulator, 0202 electrical engineering, electronic engineering, information engineering, Figure of merit, QCSE, Quantum well, business.industry, SURFACE-EMITTING LASERS, PEROT REFLECTION MODULATORS, QUANTUM-WELL STRUCTURES, WAVE-GUIDE MODULATORS, OPTICAL MODULATION, CAVITY LASER, THRESHOLD CHARACTERISTICS, REFRACTIVE-INDEX, GAAS, OPTIMIZATION, modulator, electro-absorption, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Laser, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, CMOS, Modulation, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Optoelectronics, 0210 nano-technology, business
Abstract

International audience; Electro-absorption modulators, either embedded in CMOS technology or integrated with a semiconductor laser, are of high interest for many applications such as optical communications, signal processing and 3D imaging. Recently, the integration of a surface-normal electro-absorption modulator into a vertical-cavity surface-emitting laser has been considered. In this paper we implement a simple quantum well electro-absorption model and design and optimize an asymmetric Fabry–Pérot semiconductor modulator while considering all physical properties within figures of merit. We also extend this model to account for the impact of temperature on the different parameters involved in the calculation of the absorption, such as refractive indices and exciton transition broadening. Two types of vertical modulator structures have been fabricated and experimentally characterized by reflectivity and photocurrent measurements demonstrating a very good agreement with our model. Finally, preliminary results of an electro-absorption modulator vertically integrated with a vertical-cavity surface-emitting laser device are presented, showing good modulation performances required for high speed communications.

Published
2018
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31. Increasing the Hydrophobicity of a PP Film Using a Helium/CF4 DBD Treatment at Atmospheric Pressure

Author

Rino Morent, Léon Gengembre, Ch. Leys, Edmond Payen, S. Van Vlierberghe, Etienne Schacht, N. De Geyter, Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Centrale Lille Institut (CLIL)-Université d'Artois (UA)-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Lille, Reseach Unit Plasma Technology (RUPT), Universiteit Gent = Ghent University [Belgium] (UGENT)-Department of Applied Physics, Department of organic Chemistry, Universiteit Gent = Ghent University [Belgium] (UGENT), Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Universiteit Gent = Ghent University (UGENT)-Department of Applied Physics, and Universiteit Gent = Ghent University (UGENT)

Subjects
Materials science, General Chemical Engineering, Hydrophobicity, Analytical chemistry, chemistry.chemical_element, Dielectric barrier discharge, 02 engineering and technology, Dielectric, 01 natural sciences, Contact angle, chemistry.chemical_compound, X-ray photoelectron spectroscopy, 0103 physical sciences, Polypropylene film, 010302 applied physics, chemistry.chemical_classification, Polypropylene, Atmospheric pressure, [CHIM.MATE]Chemical Sciences/Material chemistry, General Chemistry, Polymer, CF4, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Surfaces, Coatings and Films, [CHIM.POLY]Chemical Sciences/Polymers, chemistry, Fluorine, 0210 nano-technology
Abstract

International audience; Plasma surface modification is widely used to tailor the surface properties of polymeric materials. Most treatments are performed using low pressure plasma systems, but recently, atmospheric dielectric barrier discharges (DBDs) have appeared as interesting alternatives. Therefore, in this paper, an atmospheric He + CF4 DBD is used to increase the hydrophobicity of a polypropylene (PP) film. The surface characterization of the PP film is performed using contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Results show that the hydrophobic properties of the polymer films are greatly enhanced after plasma treatment as evidenced by an increased contact angle. The incorporation of fluorine on the surface is significant (45 at%), demonstrating the ability of the used DBD set-up to generate fluorine-containing functional groups on the PP surface.

Published
2008
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32. Study of the ageing behaviour of polymer films treated with a dielectric barrier discharge in air, helium and argon at medium pressure

Author

N. De Geyter, Christophe Leys, Edmond Payen, Léon Gengembre, Rino Morent, Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Centrale Lille Institut (CLIL)-Université d'Artois (UA)-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Lille, Reseach Unit Plasma Technology (RUPT), Universiteit Gent = Ghent University [Belgium] (UGENT)-Department of Applied Physics, Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), and Universiteit Gent = Ghent University (UGENT)-Department of Applied Physics

Subjects
Materials science, chemistry.chemical_element, 02 engineering and technology, Dielectric barrier discharge, 01 natural sciences, Contact angle, chemistry.chemical_compound, X-ray photoelectron spectroscopy, 0103 physical sciences, Materials Chemistry, Polyethylene terephthalate, Composite material, plasma, Helium, 010302 applied physics, Polypropylene, Argon, polymer film, [CHIM.MATE]Chemical Sciences/Material chemistry, Surfaces and Interfaces, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Surfaces, Coatings and Films, [CHIM.POLY]Chemical Sciences/Polymers, chemistry, ageing, Surface modification, DBD, 0210 nano-technology, surface modification
Abstract

Plasma treatment of polymers is gaining more and more popularity as a surface modification technique, since it offers numerous advantages over the conventional chemical processes. Plasma surface treatment is an environmentally benign, fast and versatile technology. However, it has one major disadvantage: the induced modification of the surface is not permanent, since the surface tends to recover to the untreated state. This ageing effect is due to the reorientation of induced polar chemical groups into the bulk of the material. In this paper, the ageing of polypropylene (PP) and polyethylene terephthalate (PET) films, treated with a dielectric barrier discharge operating at medium pressure (5.0 kPa) in air, helium and argon, is studied. This study is performed using contact angle measurements and X-ray photoelectron spectroscopy (XPS). Results show that the working gas used during plasma treatment has a significant influence on the ageing behaviour of both PP and PET films. The air-, helium- and argon-plasma treated PP films have a loss in treatment efficiency of 47%, 35% and 25% respectively, while the air-, helium- and argon-plasma treated PET films have a loss in treatment efficiency of 39%, 34% and 29% respectively. These results can be explained by the different cross-linking degrees of the polymer films after plasma treatment. Increasing the cross-linking degree will hinder the movement of the polymer chains and reduce the ageing effect.

Published
2007
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33. Spin and lattice excitations of aBiFeO3thin film and ceramics

Author

Carolina Adamo, Brahim Dkhil, Christelle Kadlec, Ingrid C. Infante, Xiaofei Bai, Veronica Goian, Filip Kadlec, Stanislav Kamba, Stella Skiadopoulou, D. G. Schlom, Institute of Physics [Prague], Czech Academy of Sciences [Prague] (CAS), Laboratoire Structures, Propriétés et Modélisation des solides (SPMS), Institut de Chimie du CNRS (INC)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Department of Materials Sciences and Engineering, State University of New York (SUNY), Applied Physics Department [Stanford], Stanford University, Kavli Institute at Cornell for Nanoscale Science (KIC), Cornell University [New York], Czech Academy of Sciences [Prague] (ASCR), CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Department of Applied Physics [Stanford], Stanford University [Stanford], and Cornell University

Subjects
Phase transition, Materials science, Infrared, Phonon, FOS: Physical sciences, 02 engineering and technology, 01 natural sciences, Condensed Matter::Materials Science, symbols.namesake, Spin wave, Condensed Matter::Superconductivity, 0103 physical sciences, 010306 general physics, ComputingMilieux_MISCELLANEOUS, Condensed Matter - Materials Science, Condensed matter physics, Materials Science (cond-mat.mtrl-sci), 021001 nanoscience & nanotechnology, Condensed Matter Physics, Ferroelectricity, Electronic, Optical and Magnetic Materials, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], symbols, Orthorhombic crystal system, 0210 nano-technology, Raman spectroscopy, Excitation
Abstract

International audience; 2 count the nearest and next-nearest neighbor exchange interactions, two Dzyaloshinskii-Moriya interactions and an easy-axis anisotropy. 31,35 The same model successfully described the low-energy inelastic neutron scattering spectra. 30 In contrast, Komandin et al. 15 showed IR transmission spectra with an excitation at approximately 47 cm −1 which had not been previously reported by experimental or theoretical studies. The intensive discussion in the literature concerning the nature of the spin ex-citations raises the question: which excitations are pure magnons (i.e., contribute only to the magnetic perme-ability µ) and which are electromagnons (i.e., influence at least partially the permittivity ε *)? It is worth noting that according to a recent symmetry analysis, 36 BiFeO 3 allows directional dichroism and therefore spin waves can be simultaneously excited by the electric and magnetic components of electromagnetic radiation. For more details on BiFeO 3 spin dynamics, see the review of Park et al. 37 In the current work, we report spin and lattice exci-tations in BiFeO 3 ceramics, as measured by the combination of IR reflectivity and time-domain THz transmission spectroscopy, in a temperature range from 10 to 900 K. All 13 IR-active phonon modes are observed, exhibiting softening on heating. Five low-frequency spin modes are detected from 5 K up to RT, the highest two appearing at 53 and 56 cm −1. This corresponds to the frequency range where such excitations were theoretically predicted, 31,32,35 but not experimentally confirmed up to now. At 5 K, the low-energy spin dynamics in the THz range were also studied in a varying magnetic field of up to 7 T. Softening of the (electro)magnon frequencies upon increasing the magnetic field was observed. Additionally, a BiFeO 3 epitaxial thin film grown on an orthorhombic (110) TbScO 3 single crystal substrate was studied for the first time via IR reflectance spectroscopy. II. EXPERIMENTAL DETAILS BiFeO 3 ceramics were prepared by the solid-state route. A stoichiometric mixture of Fe 2 O 3 and Bi 2 O 3 powder oxides with a purity of 99.99% was ground and uniaxially cold-pressed under 20-30 MPa pressure into 8 mm diameter pellets. The pellets were then covered by sacrificial BFO powder to avoid bismuth oxide loss from the pellet, and sintered in a tube furnace at 825 • C for8 h in air. To avoid any secondary phase formation, the samples were quenched to RT. Polished disks with a diameter of 4 mm and thicknesses of ca. 600 and 338 µm were used for the IR reflectivity and THz transmission measurements, respectively. An epitaxial BiFeO 3 thin film with a thickness of 300 nm was grown by reactive molecular-beam epitaxy on a (110) single crystal substrate. The growth parameters were the same as for the samples reported in Ref. 38. Near-normal incidence IR reflectivity spectra of the BiFeO 3 ceramics and film were obtained using a Fourier-transform IR spectrometer Bruker IFS 113v in the frequency range 20-3000 cm −1 (0.6-90 THz) at RT; for the low and high temperature measurements the spectral range was reduced to 650 cm −1. Pyroelectric deuterated triglycine sulfate detectors were used for the room-and high-temperature measurements up to 900 K, whereas a He-cooled (operating temperature 1.6 K) Si bolometer was used for the low-temperature measurements down to 10 K. A commercial high-temperature cell (SPECAC P/N 5850) was used for the high-temperature experiments. The thermal radiation from the hot sample entering the interferometer was taken into account in our spectra evaluation. THz measurements from 3 cm −1 to 60 cm −1 (0.09-1.8 THz) were performed in the transmission mode with the use of a custom-made time-domain terahertz spectrometer. In this spectrometer, a femtosecond Ti:sapphire laser oscillator (Coherent, Mira) produces a train of femtosecond pulses which generates linearly polarized broadband THz pulses in a photoconduct-ing switch TeraSED (Giga-Optics). A gated detection scheme based on electrooptic sampling with a 1 mm thick [110] ZnTe crystal as a sensor allows us to measure the time profile of the electric field of the transmitted THz pulse. The same high-temperature cell as for the IR reflectivity was used for the THz range high-temperature measurements. Oxford Instruments Opti-stat optical cryostats with mylar and polyethylene windows were used for the low-temperature THz and IR measurements , respectively. THz experiments in an external magnetic field H ext ≤ 7 T were performed upon decreasing H with an Oxford Instruments Spectromag cryostat in the Voigt configuration, where the electric component of the THz radiation E THz was set perpendicular to H ext. The IR reflectivity and THz complex (relative) per-mittivity spectra ε * (ω) were carefully fit assuming the factorized form of the dielectric function based on a generalized damped-harmonic-oscillator model: 39 ε * (ω) = ε ∞ N j=1 ω 2 LOj − ω 2 + iωγ LOj ω 2 TOj − ω 2 + iωγ TOj , (1) where ω TOj and ω LOj are the frequencies of the j-th transverse optical (TO) and longitudinal optical (LO) phonons, γ TOj and γ LOj are the corresponding damping constants, and ε ∞ denotes the high-frequency (elec-tronic) contribution to the permittivity, determined from the RT frequency-independent reflectivity tail above the phonon frequencies. The reflectivity R(ω) is related to the complex dielectric function ε * (ω) by: R(ω) = ε * (ω) − 1 ε * (ω) + 1. (2) To evaluate the IR reflectance spectra of the BiFeO 3 /TbScO 3 thin film, a model corresponding to a two-layer optical system was used. 40 The IR reflectivity spectra of the bare TbScO 3 substrate were fit first at each

Published
2015
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34. Tunable terahertz frequency comb generation using time-dependent graphene sheets

Author

Philippe Tassin, Thomas Koschny, Vincent Ginis, Costas M. Soukoulis, Applied Physics and Photonics, Applied Physics, Physics, and Faculty of Sciences and Bioengineering Sciences

Subjects
Materials science, Terahertz radiation, Superlattice, Physics::Optics, 02 engineering and technology, Conductivity, 01 natural sciences, law.invention, Frequency comb, Optics, law, 0103 physical sciences, Frequency combs, 010306 general physics, Electromagnetic pulse, business.industry, Graphene, Time-dependent electrodynamics, graphene, Metamaterial, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, metamaterials, 0210 nano-technology, business, Frequency modulation
Abstract

We investigate the interaction between electromagnetic pulses and two-dimensional current sheets whose conductivity is controlled as a function of time by the generation of photocarriers, and we discuss its applicability to tunable frequency comb generation. To this aim, we develop an analytical model that permits the calculation of the scattered waves off a thin sheet with time-dependent, dispersive sheet conductivity. We evaluate the transmitted spectrum as a function of the dispersive behavior and the modulation frequency of the number of photocarriers. We conclude that such active materials, e.g., time-dependent graphene sheets, open up the possibility to manipulate the frequency of incident pulses and, hence, could lead to highly tunable, miniaturized frequency comb generation.

Published
2015

35. Mapping of the Dynamics Induced by Orthogonal Optical Injection in Vertical-Cavity Surface-Emitting Lasers

Author

Hugo Thienpont, Ignace Gatare, J.B. Altes, Krassimir Panajotov, Marc Sciamanna, Department of Applied Physics and Photonics [Brussels] (TONA), Vrije Universiteit Brussel (VUB), Laboratoire Matériaux Optiques, Photonique et Systèmes (LMOPS), CentraleSupélec-Université de Lorraine (UL), Applied Physics and Photonics, and Vrije Universiteit Brussel

Subjects
Materials science, Physics::Optics, 02 engineering and technology, Optical chaos, 01 natural sciences, Semiconductor laser theory, law.invention, Vertical-cavity surface-emitting laser, 010309 optics, 020210 optoelectronics & photonics, Optics, law, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Electrical and Electronic Engineering, [PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], business.industry, Nonlinear optics, Condensed Matter Physics, Laser, Polarization (waves), Atomic and Molecular Physics, and Optics, Transverse mode, Injection locking, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Optoelectronics, business
Abstract

International audience; In this paper, the output characteristics of an oxide-confined AlGaAs-As quantum well vertical-cavity surface-emitting laser (VCSEL) under orthogonal optical injection are mapped as a function of the strength of the optical injection and the detuning between the injection frequency and the free-running frequency of the solitary laser, for a very large range of frequency detuning (from -82 to 89 GHz). The injection light is polarized orthogonally with respect to the solitary VCSEL output light. As the injection strength increases the VCSEL switches to the master laser polarization. Polarization switching is accompanied by a rich nonlinear dynamics, including limit cycle, wave mixing, subharmonic resonance and period doubling route to chaos. Polarization switching is found with but also without injection locking. Injection locking occurs with the slave fundamental transverse mode or, for large positive detunings, with the first-order transverse mode.

Published
2006
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36. Plasmon-Enhanced Refractometry Through Cladding Mode Excitation by a Fiber Bragg Grating in Photonic Crystal Fiber

Author

Francis Berghmans, Karima Chah, Hugo Thienpont, Tigran Baghdasaryan, Pawel Mergo, Olga Rusyakina, Thomas Geernaert, Christophe Caucheteur, Applied Physics and Photonics, Faculty of Engineering, Technology Transfer & Interface, and IR Academic Unit

Subjects
Materials science, business.industry, Physics::Optics, fiber optics sensors, PHOTONIC CRYSTAL FIBERS, Cladding mode, Atomic and Molecular Physics, and Optics, Fiber Bragg grating, Fiber bragg gratings, fiber optics sensors, photonic crystal fibers, refractive index measurement, surface plasmon resonance, Fiber Bragg gratings, Optoelectronics, A fibers, business, Refractometry, surface plasmon resonance, Excitation, Plasmon, refractive index measurement, Photonic-crystal fiber
Abstract

We report on an extrinsic surface plasmon-enhancedrefractometer based on cladding mode resonance excitation in a photonic crystal fiber (PCF) equipped with a straight fiber Bragggrating (FBG). First, we show that the lattice pitch and the air hole diameter of the PCF microstructure define the spectral locationof the excited cladding mode resonances. Second, we demonstrate that if the PCF parameters are properly selected, those resonancesare sensitive to increases in steps of 1×10−4 refractive index units(RIU) of the refractive index value close to that of water. To thebest of our knowledge, this is the first time that the sensitivity of PCF cladding mode resonances to refractive index changesin water-based solutions is reported. We achieved experimental values of 40.3 nm/RIU in terms of wavelength sensitivity and −801dB/RIU in terms of amplitude sensitivity. The performance of our sensor is therefore comparable to that of tilted FBGs in step-indexfibers used for water refractometry, which indicates the potential ofour PCF sensor for biosensing. In addition, the sensor fabricationdoes not require any post-processing such as etching or polishing,which allows preserving the integrity of the fiber probe. Finally, thenarrowspectrum within which the PCF operates, allows envisagingmulti-target detection with a single fiber probe by using cascadedwavelength-multiplexed gratings.

Published
2022
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37. Epitaxial hexagonal boron nitride on Ir(111): A work function template

Author

Ari P. Seitsonen, Thomas Demonchaux, Peter Liljeroth, Sampsa K. Hämäläinen, Fabian Schulz, Robert Drost, Department of Applied Physics [Aalto], Aalto University, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Institut für Chemie, Universität Zürich [Zürich] = University of Zurich (UZH), This research made use of the Aalto Nanomicroscopy Center (Aalto NMC) facilities and was supported by the European Research Council (ERC-2011-StG No. 278698 'PRECISE-NANO'), the Academy of Finland (Centre of Excellence in Low Temperature Quantum Phenomena and Devices No. 250280), and the Finnish Academy of Science and Letters. Computing time was awarded by CSCS (Centro Svizzero di Calcolo Scientifico) under the Project No. s425., University of Zurich, Department of Applied Physics, and Aalto-yliopisto

Subjects
10120 Department of Chemistry, Ir(111), 3104 Condensed Matter Physics, Materials science, ta221, FOS: Physical sciences, chemistry.chemical_element, Nanotechnology, 02 engineering and technology, Epitaxy, 01 natural sciences, law.invention, chemistry.chemical_compound, law, 540 Chemistry, 0103 physical sciences, Monolayer, Work function, Thin film, density-functional theory, 010306 general physics, Boron, PACS: 68.37.Ef, 73.20.−r, 73.22.−f, 81.15.Gh, ta218, Condensed Matter - Materials Science, Superstructure, ta214, ta114, Materials Science (cond-mat.mtrl-sci), 2504 Electronic, Optical and Magnetic Materials, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, boron nitride, Crystallography, chemistry, Boron nitride, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], scanning tunneling microscopy, Scanning tunneling microscope, 0210 nano-technology
Abstract

Hexagonal boron nitride (h-BN) is a prominent member in the growing family of two-dimensional materials with potential applications ranging from being an atomically smooth support for other 2D materials to templating growth of molecular layers. We have studied the structure of monolayer h-BN grown by chemical vapour deposition on Ir(111) by low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS) experiments and state-of-the-art density functional theory (DFT) calculations. The lattice-mismatch between the h-BN and Ir(111) surface results in the formation of a moir\'e superstructure with a periodicity of $\sim$29 \AA\ and a corrugation of $\sim$0.4 \AA. By measuring the field emission resonances above the h-BN layer, we find a modulation of the work function within the moir\'e unit cell of $\sim$0.5 eV. DFT simulations for a 13-on-12 h-BN/Ir(111) unit cell confirm our experimental findings and allow us to relate the change in the work function to the subtle changes in the interaction between boron and nitrogen atoms and the underlying substrate atoms within the moir\'e unit cell. Hexagonal boron nitride on Ir(111) combines weak topographic corrugation with a strong work function modulation over the moir\'e unit cell. This makes h-BN/Ir(111) a potential substrate for electronically modulated thin film and hetero-sandwich structures., Comment: 8 pages, 5 figures

Published
2014
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38. Wavelength tuning speed in semiconductor ring lasers using on-chip filtered optical feedback

Author

Verschaffelt, G., Khoder, M., Nguimdo, R.M., Leijtens, X.J.M., Bolk, J., Danckaert, J., Vivien, L., Hankanen, S., Pavesi, L., Pelli, S., Photonic Integration, NanoLab@TU/e, Applied Physics, Physics, and Applied Physics and Photonics

Subjects
Optical amplifier, tunable laser, Distributed feedback laser, Materials science, business.industry, Photonic integrated circuit, Physics::Optics, Semiconductor ring laser, law.invention, Switching time, Optics, semiconductor ring laser, law, Optical cavity, Optoelectronics, Semiconductor optical gain, business, Tunable laser
Abstract

Wavelength tunable and switchable lasers are widely used in telecommunication networks as they allow flexible wavelength division multiplexing, fast optical signal routing, and all-optical signal processing. In this work, we characterize the wavelength switching speed of a tunable semiconductor ring lasers using filtered optical feedback. Semiconductor ring lasers nowadays are promising sources in photonic integrated circuits because they do not require cleaved facets or mirrors to form a laser cavity. They are interesting from a nonlinear dynamics point of view due to the existence of two counter propagating modes that interact with each other which allows semiconductor ring lasers to be used as all-optical switches and as all-optical memories. The wavelength of the semiconductor ring laser is controlled by a feedback section which consists of two arrayed waveguide gratings, four semiconductor optical amplifiers and waveguides to connect the different components. The filtered optical feedback is realized by employing the two arrayed waveguide gratings to split/recombine light into different wavelength channels. Semiconductor optical amplifiers are placed in the feedback loop in order to control the feedback strength of each wavelength channel independently. The switching is achieved by changing the currents injected in the semiconductor optical amplifier gates. Experimentally, we observe a wavelength transition time of 5 ns. However, we also noticed a non-negligible delay in the switching process. We discuss this delay time and the different parameters which have an effect on it. We can numerically reproduce the experimental results using rate equations taking into account the effect of spontaneous emission. The simulations also demonstrate that the wavelength transition time and the delay can be further decreased by controlling the phase in the feedback section and by increasing the strength of the feedback.

Published
2014
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39. Core level binding energies of functionalized and defective graphene

Author

Paula Havu, Mathias P. Ljungberg, M. Kaukonen, Toma Susi, Paola Ayala, Esko I. Kauppinen, Perustieteiden korkeakoulu, School of Science, Teknillisen fysiikan laitos, Department of Applied Physics, Aalto-yliopisto, Aalto University, Department of Applied Physics [Aalto], Faculty of Physics [Vienna], Universität Wien, Laboratoire Ondes et Matière d'Aquitaine (LOMA), and Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS)

Subjects
X-ray photoelectron spectroscopy, Materials science, Binding energy, Ab initio, General Physics and Astronomy, lcsh:Chemical technology, lcsh:Technology, Molecular physics, DFT, Full Research Paper, law.invention, law, Computational chemistry, Vacancy defect, XPS, Molecule, Periodic boundary conditions, Nanotechnology, lcsh:TP1-1185, General Materials Science, Electrical and Electronic Engineering, lcsh:Science, binding energies, defects, density functional theory, lcsh:T, Graphene, Physics, graphene, core level, lcsh:QC1-999, Nanoscience, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], lcsh:Q, Density functional theory, lcsh:Physics
Abstract

International audience; X-ray photoelectron spectroscopy (XPS) is a widely used tool for studying the chemical composition of materials and it is a standard technique in surface science and technology. XPS is particularly useful for characterizing nanostructures such as carbon nanomaterials due to their reduced dimensionality. In order to assign the measured binding energies to specific bonding environments, reference energy values need to be known. Experimental measurements of the core level signals of the elements present in novel materials such as graphene have often been compared to values measured for molecules, or calculated for finite clusters. Here we have calculated core level binding energies for variously functionalized or defected graphene by delta Kohn-Sham total energy differences in the real-space grid-based projector-augmented wave density functional theory code (GPAW). To accurately model extended systems, we applied periodic boundary conditions in large unit cells to avoid computational artifacts. In select cases, we compared the results to all-electron calculations using an ab initio molecular simulations (FHI-aims) code. We calculated the carbon and oxygen 1s core level binding energies for oxygen and hydrogen functionalities such as graphane-like hydrogenation, and epoxide, hydroxide and carboxylic functional groups. In all cases, we considered binding energy contributions arising from carbon atoms up to the third nearest neighbor from the functional group, and plotted C 1s line shapes by using experimentally realistic broadenings. Furthermore, we simulated the simplest atomic defects, namely single and double vacancies and the Stone-Thrower-Wales defect. Finally, we studied modifications of a reactive single vacancy with O and H functionalities, and compared the calculated values to data found in the literature.

Published
2014
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40. Dielectric meta-atoms coupled by nonresonant metallic antennas

Author

Philippe Tassin, Aditya Jain, Costas M. Soukoulis, Thomas Koschny, Applied Physics, and Applied Physics and Photonics

Subjects
Materials science, business.industry, Resonance, Metamaterial, Physics::Optics, Dielectric, Physics::Classical Physics, Atomic and Molecular Physics, and Optics, Metal, Condensed Matter::Materials Science, Quality (physics), Negative refraction, visual_art, visual_art.visual_art_medium, Optoelectronics, Optical rotation, business, Instrumentation, Circular polarization
Abstract

We demonstrate a new class of metamaterials with dielectric meta-atoms coupled to the incident waves by nonresonant metallic antennas. The storage of energy in the dielectric enables high-quality resonances in negative-permittivity and negative-permeability sheet metamaterials.

Published
2014

41. Integrated Small-Sized Semiconductor Ring Laser With Novel Retro-Reflector Cavity

Author

Marc Sorel, Jan Danckaert, Zhuoran Wang, Gabor Mezosi, Yi Shu, G. Verschaffelt, Siyuan Yu, Physics, Applied Physics and Photonics, and Applied Physics

Subjects
Materials science, business.industry, Parabolic reflector, Physics::Optics, Semiconductor ring laser, Ring (chemistry), Laser, Atomic and Molecular Physics, and Optics, Retroreflector, Electronic, Optical and Magnetic Materials, Semiconductor laser theory, law.invention, Optics, Semiconductor, law, semiconductor ring laser (SRL), Optoelectronics, optical planar waveguide, semiconductor lasers, Electrical and Electronic Engineering, Photonics, business, integrated optoelectronics
Abstract

We have successfully designed and fabricated 1.55-mu m semiconductor ring lasers with novel parabolic mirror retro-reflector cavities. The parabolic mirror is designed by means of ray-tracing and finite-difference time-domain to optimize its shape and position. The fabricated devices, with a range of sizes down to an equivalent circular ring radius of 16 mu m, operate in continuous-wave mode at room temperature. Threshold current of 22 mA and output power up to 140 mu W have been achieved for the smallest device. These devices are suitable for high-speed all-optical signal processing and digital photonic functions.

Published
2008
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42. Electrostatic Discovery Atomic Force Microscopy

Author

Peter Liljeroth, Niko Oinonen, Adam S. Foster, Benjamin Alldritt, Ondřej Krejčí, Fedor Urtev, Filippo Federici Canova, Shuning Cai, Juho Kannala, Chen Xu, Surfaces and Interfaces at the Nanoscale, Department of Applied Physics, Department of Computer Science, Aalto University, Computer Science Professors, and Aalto-yliopisto

Subjects
Materials science, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, FOS: Physical sciences, General Physics and Astronomy, High resolution, Nanotechnology, 02 engineering and technology, Electronic structure, Molecular systems, 01 natural sciences, Atomic units, Article, Scanning probe microscopy, chemical identification, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, General Materials Science, 010306 general physics, tip functionalization, atomic force microscopy, Hardware_MEMORYSTRUCTURES, Condensed Matter - Mesoscale and Nanoscale Physics, Atomic force microscopy, General Engineering, Computational Physics (physics.comp-ph), 021001 nanoscience & nanotechnology, Electrostatics, electrostatics, Characterization (materials science), machine learning, 0210 nano-technology, Physics - Computational Physics
Abstract

openaire: EC/H2020/788185/EU//E-DESIGN | openaire: EC/H2020/845060/EU//QMKPFM | openaire: EC/H2020/897828/EU//EIM While offering high resolution atomic and electronic structure, scanning probe microscopy techniques have found greater challenges in providing reliable electrostatic characterization on the same scale. In this work, we offer electrostatic discovery atomic force microscopy, a machine learning based method which provides immediate maps of the electrostatic potential directly from atomic force microscopy images with functionalized tips. We apply this to characterize the electrostatic properties of a variety of molecular systems and compare directly to reference simulations, demonstrating good agreement. This approach offers reliable atomic scale electrostatic maps on any system with minimal computational overhead.

Published
2021
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43. Two-dimensional Cahn-Hilliard simulations for coarsening kinetics of spinodal decomposition in binary mixtures

Author

Jens Harting, Björn König, Olivier Ronsin, and Applied Physics and Science Education

Subjects
Condensed Matter - Materials Science, Materials science, Characteristic length, Spinodal decomposition, Kinetics, General Physics and Astronomy, Thermodynamics, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Condensed Matter - Soft Condensed Matter, Computational Physics (physics.comp-ph), Microstructure, Condensed Matter::Soft Condensed Matter, Reaction rate constant, Phase (matter), ddc:540, Exponent, Soft Condensed Matter (cond-mat.soft), Physical and Theoretical Chemistry, Constant (mathematics), Physics - Computational Physics
Abstract

The evolution of the microstructure due to spinodal decomposition in phase separated mixtures has a strong impact on the final material properties. In the late stage of coarsening, the system is characterized by the growth of a single characteristic length scale L ∼ Ctα. To understand the structure–property relationship, the knowledge of the coarsening exponent α and the coarsening rate constant C is mandatory. Since the existing literature is not entirely consistent, we perform phase field simulations based on the Cahn–Hilliard equation. We restrict ourselves to binary mixtures using a symmetric Flory–Huggins free energy and a constant composition-independent mobility term and show that the coarsening for off-critical mixtures is slower than the expected t1/3-growth. Instead, we find α to be dependent on the mixture composition and associate this with the observed morphologies. Finally, we propose a model to describe the complete coarsening kinetics including the rate constant C.

Published
2021
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44. Interface engineering of bi-layer semiconductor SrCoSnO3-δ-CeO2-δ heterojunction electrolyte for boosting the electrochemical performance of low-temperature ceramic fuel cell

Author

Muhammad Yousaf, Peter Lund, M.A.K. Yousaf Shah, Muhammad Asghar, Bin Zhu, Sajid Rauf, Zuhra Tayyab, Naveed Mushtaq, Muhammad Imran, Southeast University, Nanjing, Hubei University, University of Agricultur Multan, Department of Applied Physics, Aalto-yliopisto, and Aalto University

Subjects
Materials science, Renewable Energy, Sustainability and the Environment, Energy Engineering and Power Technology, Ionic bonding, Heterojunction, Electrolyte, Ceramic fuel cell, Condensed Matter Physics, Electrochemistry, Fuel Technology, Chemical engineering, visual_art, Built-in electric field, visual_art.visual_art_medium, Ionic conductivity, Ceramic, Bi-layer electrolyte, Semiconductor heterojunction, Power density, Perovskite (structure)
Abstract

Funding Information: This work was supported Southeast University (SEU) PROJET # 3203002003A1 and National Natural Science Foundation of China (NSFC) under the grant # 51772080 and 11604088 . Dr. Asghar thanks the Hubei overseas Talent 100 program (as a distinguished professor at Hubei University) and Academy of Finland (Grant No. 13329016, 13322738) for their support. Publisher Copyright: © 2021 The Author(s) A comparative study is performed to investigate the electrochemical performance of the low-temperature ceramic fuel cells (CFCs) utilizing two different novel electrolytes. First, a perovskite semiconductor SrCo0.3Sn0.7O3-δ was used as an electrolyte in CFCs due to its modest ionic conductivity (0.1 S/cm) and demonstrated an acceptable power density of 360 mW/cm2 at 520 °C. The performance of the cell was primarily limited due to the moderate ionic transport in the electrolyte. In order to improve the ionic conductivity, a new strategy of using a novel bi-layer electrolyte concept consist of SrCo0.3Sn0.7O3-δ and CeO2-δ in CFCs. These bi-layers of two electrolytes have successfully established heterojunction which considerably improved the ionic conductivity (0.2 S/cm) and enhance the open-circuit voltage of the cell from 0.98 V to 1.001 V. Moreover, the CFCs utilizing bi-layer electrolyte have produced a remarkable power density of 672 mW/cm2 at 520 °C. This enhancement of ionic conduction, power density and blockage of electron conduction in the bi-layer electrolyte was studied via band alignment mechanism based on proposed p-n heterojunction. Our work presents a promising methodology for developing advanced low-temperature CFC electrolytes.

Published
2021
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45. Digitally tunable dual wavelength emission from semiconductor ring lasers with filtered optical feedback

Author

Romain Modeste Nguimdo, Guy Verschaffelt, Xaveer Leijtens, Jan Danckaert, Jeroen Bolk, Mulham Khoder, Applied Physics, Physics, Applied Physics and Photonics, Photonic Integration, and NanoLab@TU/e

Subjects
SRL, Materials science, Physics and Astronomy (miscellaneous), photonics, Physics::Optics, 02 engineering and technology, 01 natural sciences, Waveguide (optics), law.invention, 010309 optics, 020210 optoelectronics & photonics, Zero-dispersion wavelength, Optics, law, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Instrumentation, Optical amplifier, business.industry, Amplifier, Semiconductor ring laser, Feedback loop, Laser, Optoelectronics, Photonics, business
Abstract

We report on a novel integrated approach to obtain dual wavelength emission from a semiconductor laser based on on-chip filtered optical feedback. Using this approach, we show experiments and numerical simulations of dual wavelength emission of a semiconductor ring laser. The filtered optical feedback is realized on-chip by employing two arrayed waveguide gratings to split/recombine light into different wavelength channels. Semiconductor optical amplifiers are placed in the feedback loop in order to control the feedback strength of each wavelength channel independently. By tuning the current injected into each of the amplifiers, we can effectively cancel the gain difference between the wavelength channels due to fabrication and material dichroism, thus resulting in stable dual wavelength emission. We also explore the accuracy needed in the operational parameters to maintain this dual wavelength emission.

Published
2013

46. Metamaterial-Based Approach to Enhance Optical Gradient Forces

Author

Vincent Ginis, Irina Veretennicoff, Costas M. Soukoulis, Philippe Tassin, Applied Physics, Physics, and Applied Physics and Photonics

Subjects
Materials science, Silicon photonics, applied physics, business.industry, Optical forces, Optical force, Nanophotonics, Transformation optics, photonics, Metamaterial, Physics::Optics, Microstructured optical fiber, Waveguide (optics), optics, Optics, metamaterials, thin films, Optoelectronics, business, Microphotonics, Computer Science::Databases
Abstract

We show how transformation optics can enhance optical forces between two optical waveguides by several orders of magnitude by altering the perceived distance between the waveguides. This transformation can be implemented using single-negative metamaterial films.

Published
2013

47. Enhanced cell-material interactions on medium-pressure plasma-treated polyhydroxybutyrate/polyhydroxyvalerate

Author

Rino Morent, Ria Cornelissen, A. Beaurain, Nathalie De Geyter, Tinneke Jacobs, Heidi Declercq, Peter Dubruel, Edmond Payen, Christophe Leys, Universiteit Gent = Ghent University [Belgium] (UGENT), Reseach Unit Plasma Technology (RUPT), Universiteit Gent = Ghent University [Belgium] (UGENT)-Department of Applied Physics, Faculty of Sciences, Polymer Chemistry and Biomaterials Research Group, Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Centrale Lille Institut (CLIL)-Université d'Artois (UA)-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Lille, Universiteit Gent = Ghent University (UGENT), Universiteit Gent = Ghent University (UGENT)-Department of Applied Physics, and Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)

Subjects
Male, Materials science, Plasma Gases, Polyesters, Biomedical Engineering, Biocompatible Materials, 02 engineering and technology, Dielectric barrier discharge, Cell Communication, 01 natural sciences, Biomaterials, Polyhydroxybutyrate, Contact angle, Electricity, 0103 physical sciences, Prohibitins, Pressure, Humans, [CHIM]Chemical Sciences, Composite material, Cell adhesion, FOIL method, Cells, Cultured, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, Glow discharge, Photoelectron Spectroscopy, Metals and Alloys, Fibroblasts, 021001 nanoscience & nanotechnology, Polyester, Chemical engineering, Microscopy, Fluorescence, Ceramics and Composites, Surface modification, Thermodynamics, 0210 nano-technology
Abstract

In this article, a medium-pressure DBD plasma treatment is used to improve the cell–material interaction of a polyhydroxybutyrate/polyhydroxyvalerate (PHB/PHV) film. PHB/PHV is a biodegradable natural polyester, used for different biomedical applications, including sutures, repair devices, and bone marrow scaffolds. The cell adhesion onto PHB/PHV is far less than optimal due to inadequate surface properties, and a surface modification is usually necessary to be able to use the full potential. Medium-pressure plasma treatments, in different atmospheres, are used to change the surface properties of a PHB/PHV foil. The hydrophilic character could be increased, as shown by water contact angle measurements. X-ray photoelectron spectroscopy (XPS) revealed an increased oxygen and nitrogen content. Cell culture test with human foreskin fibroblasts showed that the plasma was able to improve cell adhesion (both quantitatively and qualitatively). Both an increase in the number of adherent cells and an improved morphology were obtained after plasma treatment. After 7 days, a confluent cell layer could be observed on plasma-treated samples. The differences between the three discharge gases are negligible when looking at the improved cell–material interactions. From economical point of view, treatments in air are thus the best choice. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.

Published
2013
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48. Enhancing optical gradient forces with metamaterials

Author

Costas M. Soukoulis, Irina Veretennicoff, Vincent Ginis, Philippe Tassin, Physics, Applied Physics and Photonics, Applied Physics, and Faculty of Sciences and Bioengineering Sciences

Subjects
Materials science, Optical force, Nanophotonics, photonics, optical force, FOS: Physical sciences, General Physics and Astronomy, Physics::Optics, law.invention, Resonator, Optics, law, Transformation optics, Condensed Matter - Materials Science, applied physics, business.industry, Materials Science (cond-mat.mtrl-sci), Metamaterial, Pressure-gradient force, optics, metamaterials, Optoelectronics, Photonics, business, Waveguide, Physics - Optics, Optics (physics.optics)
Abstract

We demonstrate how the optical gradient force between two waveguides can be enhanced using transformation optics. A thin layer of double-negative or single-negative metamaterial can shrink the interwaveguide distance perceived by light, resulting in a more than tenfold enhancement of the optical force. This process is remarkably robust to the dissipative loss normally observed in metamaterials. Our results provide an alternative way to boost optical gradient forces in nanophotonic actuation systems and may be combined with existing resonator-based enhancement methods to produce optical forces with an unprecedented amplitude., Comment: 5 pages, 4 figures; supplemental information available from APS

Published
2013

49. Enhanced light extraction from InGaN/GaN quantum wells with silver gratings

Author

Estelle Homeyer, Filip Tuomisto, Jani Oksanen, Henri Nykänen, Clementine Symonds, Sami Suihkonen, Jukka Tulkki, Joel Bellessa, Toufik Sadi, Markku Sopanen, Päivi Mattila, Perustieteiden korkeakoulu, School of Science, Teknillisen fysiikan laitos, Department of Applied Physics, Aalto-yliopisto, Aalto University, Institut Lumière Matière [Villeurbanne] (ILM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Department of micro and nanosciences, Department of Biomedical Engineering and Computational Science (BECS), Aalto University School of Science and Technology [Aalto, Finland], and Department of Applied Physics [Aalto]

Subjects
Plasmons, Diffraction, Materials science, Physics and Astronomy (miscellaneous), Polymers, Thin films, ta221, Physics::Optics, 02 engineering and technology, semiconductors, Grating, 01 natural sciences, law.invention, [SPI]Engineering Sciences [physics], Condensed Matter::Materials Science, Optics, law, 0103 physical sciences, [CHIM]Chemical Sciences, Thin film, ta216, Gratings, Diffraction grating, ta116, Plasmon, Quantum well, Reflectometry, [PHYS]Physics [physics], 010302 applied physics, ta214, ta213, ta114, business.industry, Physics, diffraction gratings, Transition metals, 021001 nanoscience & nanotechnology, Light emitting diodes, Optical waveguides, Quantum wells, Semiconductor, quantum wells, Semiconductors, Optoelectronics, 0210 nano-technology, business, Light-emitting diode
Abstract

International audience; We demonstrate that an extraction enhancement by a factor of 2.8 can be obtained for a GaN quantum well structure using metallic nanostructures, compared to a flat semiconductor. The InGaN/GaN quantum well is inserted into a dielectric waveguide, naturally formed in the structure, and a silver grating is deposited on the surface and covered with a polymer film. The polymer layer greatly improves the extraction compared to a single metallic grating. The comparison of the experiments with simulations gives strong indications on the key role of weakly guided modes in the polymer layer diffracted by the grating.

Published
2013
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50. Defect mediated manipulation of nanoclusters on an insulator

Author

Teemu Hynninen, Clemens Barth, Adam S. Foster, Gregory Cabailh, Perustieteiden korkeakoulu, School of Science, Teknillisen fysiikan laitos, Department of Applied Physics, Aalto-yliopisto, Aalto University, COMP Centre of Excellence - Department of Applied Physics, Tampere University of Technology [Tampere] (TUT), Oxydes en basses dimensions (INSP-E9), Institut des Nanosciences de Paris (INSP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), and Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Microscope, Materials science, Nanostructure, SPM, Insulator (electricity), 02 engineering and technology, Bioinformatics, 01 natural sciences, gold clusters, Article, law.invention, Nanoclusters, law, 0103 physical sciences, Cluster (physics), 010306 general physics, Anisotropy, Nanoscopic scale, [PHYS]Physics [physics], Multidisciplinary, Physics, 021001 nanoscience & nanotechnology, electronic structure, Chemical physics, manipulation, Nanometre, nanoparticles, 0210 nano-technology
Abstract

With modern scanning probe microscopes, it is possible to manipulate surface structures even at the atomic level. However, manipulation of nanoscale objects such as clusters is often more relevant and also more challenging due to the complicated interactions between the surface, cluster and apparatus. We demonstrate the manipulation of nanometer scale gold clusters on the NaCl(001) surface with a non-contact atomic force microscope, and show that the movement of clusters is in certain cases constrained to specific crystallographic directions. First principles calculations explain this kinetic anisotropy as the result of the cluster attaching to surface defects: cation vacancies allow the clusters to bond in such a way that they only move in one direction. Constraining the movement of clusters could be exploited in the construction of nanostructures or nanomechanical devices, and the manipulation signatures may also be used for identifying cluster-defect complexes.

Published
2013
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