Change search
Refine search result
1 - 16 of 16
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Baghban, Mohammad Amin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Integrated Nanophotonic Devices in Lithium Niobate2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Lithium niobate (LN) is a ferroelectric crystal offering a broad transparency spectrum, together with excellent electro-optic and nonlinear optical properties. Thanks to them, LN is setting the standard for quantum optics and telecommunications in critical applications such as ultrafast modulation and frequency conversion. The development of a reliable nanophotonic platform in LN can be expected to effectively leverage all such appealing functionalities in compact and integrated formats and provide important and complementary functionalities to current silicon-photonics platforms.

    This thesis encompasses systematic and consistent efforts with the goal to achieve the key building blocks for a comprehensive integrated nanophotonic platform in LN. It involves work on the technology side, sustained and complemented by modelling and experiments, ultimately leading to the demonstration of a few novel devices.

    Ultrahigh field confinement in nanophotonic waveguides is accompanied by the appearance of non-negligible longitudinal components in the guided optical fields. By fabricating high-quality LN nanopillars and analyzing with theory and experiments their second harmonic generation (SHG) response, we provide evidence for the existence of longitudinal field components and demonstrate the possibility to reshape the SHG polar emission properties of these submicrometric waveguides by fine-tuning the nanopillar size.

    This thesis also presents a different technological approach, allowing the fabrication of photonic wires as small as 250 nm with lengths up to 1 cm on LN-on-insulator (LNOI), suitable for upscaling to photonic integrated circuit (PIC) architectures. By optimizing the fabrication process, the propagation losses of single-mode waveguides at telecom wavelengths on this platform were brought down from 76 to 1.13 dB/cm. Fine-pitch waveguide structuring was also successfully achieved, enabling LNOI-to-fiber grating couplers and waveguide Bragg gratings, the latter featuring record extinction ratios in LNOI (45 dB), comparable to the state of the art in silicon.

    The thesis involves also theoretical work on the design of photonic wires where the interplay between LN and waveguide birefringence is used to achieve polarization-insensitive operation for the fundamental guided modes.

    Finally, two demonstrators are provided for novel and emerging applications of LN to the life sciences, using LNOI surface-patterned templates for enhanced Raman spectroscopy and LN templates for controlled neuron growth and manipulation in microfluidic environments, respectively.

  • 2.
    Brodu, Annalisa
    et al.
    Univ Utrecht, Debye Inst Nanomat Sci, NL-3584 CC Utrecht, Netherlands..
    Ballottin, Mariana V.
    Radboud Univ Nijmegen, High Field Magnet Lab, HFML EMFL, NL-6525 ED Nijmegen, Netherlands..
    Buhot, Jonathan
    Radboud Univ Nijmegen, High Field Magnet Lab, HFML EMFL, NL-6525 ED Nijmegen, Netherlands..
    van Harten, Elleke J.
    Univ Utrecht, Debye Inst Nanomat Sci, NL-3584 CC Utrecht, Netherlands..
    Dupont, Dorian
    Univ Ghent, Phys & Chem Nanostruct, B-9000 Ghent, Belgium..
    La Porta, Andrea
    Univ Antwerp, EMAT, Electron Microscopy Mat Res, B-2020 Antwerp, Belgium..
    Prins, P. Tim
    Univ Utrecht, Debye Inst Nanomat Sci, NL-3584 CC Utrecht, Netherlands..
    Tessier, Mickael D.
    Univ Ghent, Phys & Chem Nanostruct, B-9000 Ghent, Belgium..
    Versteegh, Marijn A. M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Bals, Sara
    Univ Antwerp, EMAT, Electron Microscopy Mat Res, B-2020 Antwerp, Belgium..
    Hens, Zeger
    Univ Ghent, Phys & Chem Nanostruct, B-9000 Ghent, Belgium..
    Rabouw, Freddy T.
    Univ Utrecht, Debye Inst Nanomat Sci, NL-3584 CC Utrecht, Netherlands..
    Christianen, Peter C. M.
    Radboud Univ Nijmegen, High Field Magnet Lab, HFML EMFL, NL-6525 ED Nijmegen, Netherlands..
    Donega, Celso de Mello
    Univ Utrecht, Debye Inst Nanomat Sci, NL-3584 CC Utrecht, Netherlands..
    Vanmaekelbergh, Daniel
    Univ Utrecht, Debye Inst Nanomat Sci, NL-3584 CC Utrecht, Netherlands..
    Exciton Fine Structure and Lattice Dynamics in InP/ZnSe Core/Shell Quantum Dots2018In: ACS Photonics, E-ISSN 2330-4022, Vol. 5, no 8, p. 3353-3362Article in journal (Refereed)
    Abstract [en]

    Nanocrystalline InP quantum dots (QDs) hold promise for heavy-metal-free optoelectronic applications due to their bright and size tunable emission in the visible range. Photochemical stability and high photoluminescence (PL) quantum yield are obtained by a diversity of epitaxial shells around the InP core. To understand and optimize the emission line shapes, the exciton fine structure of InP core/shell QD systems needs be investigated. Here, we study the exciton fine structure of InP/ZnSe core/shell QDs with core diameters ranging from 2.9 to 3.6 nm (PL peak from 2.3 to 1.95 eV at 4 K). PL decay measurements as a function of temperature in the 10 mK to 300 K range show that the lowest exciton fine structure state is a dark state, from which radiative recombination is assisted by coupling to confined acoustic phonons with energies ranging from 4 to 7 meV, depending on the core diameter. Circularly polarized fluorescence line-narrowing (FLN) spectroscopy at 4 K under high magnetic fields (up to 30 T) demonstrates that radiative recombination from the dark F = +/- 2 state involves acoustic and optical phonons, from both the InP core and the ZnSe shell. Our data indicate that the highest intensity FLN peak is an acoustic phonon replica rather than a zero-phonon line, implying that the energy separation observed between the F = +/- 1 state and the highest intensity peak in the FLN spectra (6 to 16 meV, depending on the InP core size) is larger than the splitting between the dark and bright fine structure exciton states.

  • 3.
    Chi, Xiaoming
    et al.
    Tianjin Univ, Sch Precis Instrument & Optoelect Engn, Tianjin 300072, Peoples R China.;Minist Educ, Key Lab Optoelect Informat Sci & Technol, Tianjin 300072, Peoples R China..
    Zou, Kai
    Tianjin Univ, Sch Precis Instrument & Optoelect Engn, Tianjin 300072, Peoples R China.;Minist Educ, Key Lab Optoelect Informat Sci & Technol, Tianjin 300072, Peoples R China..
    Gu, Chao
    Tianjin Univ, Sch Precis Instrument & Optoelect Engn, Tianjin 300072, Peoples R China.;Minist Educ, Key Lab Optoelect Informat Sci & Technol, Tianjin 300072, Peoples R China..
    Zichi, Julien
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Cheng, Yuhao
    Tianjin Univ, Sch Precis Instrument & Optoelect Engn, Tianjin 300072, Peoples R China.;Minist Educ, Key Lab Optoelect Informat Sci & Technol, Tianjin 300072, Peoples R China..
    Hu, Nan
    Tianjin Univ, Sch Precis Instrument & Optoelect Engn, Tianjin 300072, Peoples R China.;Minist Educ, Key Lab Optoelect Informat Sci & Technol, Tianjin 300072, Peoples R China..
    Lan, Xiaojian
    Tianjin Univ, Sch Precis Instrument & Optoelect Engn, Tianjin 300072, Peoples R China.;Minist Educ, Key Lab Optoelect Informat Sci & Technol, Tianjin 300072, Peoples R China..
    Chen, Shufan
    Tianjin Univ, Sch Precis Instrument & Optoelect Engn, Tianjin 300072, Peoples R China.;Minist Educ, Key Lab Optoelect Informat Sci & Technol, Tianjin 300072, Peoples R China..
    Lin, Zuzeng
    KTH, School of Engineering Sciences (SCI), Applied Physics. Tianjin Univ, Sch Precis Instrument & Optoelect Engn, Tianjin 300072, Peoples R China.;Minist Educ, Key Lab Optoelect Informat Sci & Technol, Tianjin 300072, Peoples R China..
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Hu, Xiaolong
    Tianjin Univ, Sch Precis Instrument & Optoelect Engn, Tianjin 300072, Peoples R China.;Minist Educ, Key Lab Optoelect Informat Sci & Technol, Tianjin 300072, Peoples R China..
    Fractal superconducting nanowire single-photon detectors with reduced polarization sensitivity2018In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 43, no 20, p. 5017-5020Article in journal (Refereed)
    Abstract [en]

    We demonstrate superconducting nanowire single-photon detectors (SNSPDs) based on a fractal design of the nanowires to reduce the polarization sensitivity of detection efficiency. We patterned niobium titanium nitride thin films into Peano curves with a linewidth of 100 nm and integrated the nanowires with optical microcavities to enhance their optical absorption. At a base temperature of 2.6 K, the fractal SNSPD exhibited a polarization-maximum device efficiency of 67% and a polarization-minimum device efficiency of 61% at a wavelength of 1550 nm. Therefore, the polarization sensitivity, defined as their ratio, was 1.1, lower than the polarization sensitivity of the SNSPDs in the meander design. The reduced polarization sensitivity of the detector could be maintained for higher-order spatial modes in multimode optical fibers and could tolerate misalignment between the optical mode and the detector. This fractal design is applicable to both amorphous and polycrystalline materials that are commonly used for making SNSPDs.

  • 4.
    Garcia-Guirado, Jose
    et al.
    Barcelona Inst Sci & Technol, ICFO Inst Ciencies Foton, Barcelona 08860, Spain..
    Svedendahl, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics. Barcelona Inst Sci & Technol, ICFO Inst Ciencies Foton, Barcelona 08860, Spain.
    Puigdollers, Joaquim
    Univ Politecn Cataluna, Dept Engn Elect, ES-08034 Barcelona, Spain..
    Quidantt, Romain
    Barcelona Inst Sci & Technol, ICFO Inst Ciencies Foton, Barcelona 08860, Spain.;ICREA, Barcelona 08010, Spain..
    Enantiomer-Selective Molecular Sensing Using Racemic Nanoplasmonic Arrays2018In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 18, no 10, p. 6279-6285Article in journal (Refereed)
    Abstract [en]

    Building blocks of life show well-defined chiral symmetry which has a direct influence on their properties and role in Nature. Chiral molecules are typically characterized by optical techniques such as circular dichroism (CD) where they exhibit signatures in the ultraviolet frequency region. Plasmonic nanostructures have the potential to enhance the sensitivity of chiral detection and translate the molecular chirality to the visible spectral range. Despite recent progress, to date, it remains unclear which properties plasmonic sensors should exhibit to maximize this effect and apply it to reliable enantiomer discrimination. Here, we bring further insight into this complex problem and present a chiral plasmonic sensor composed of a racemic mixture of gammadions with no intrinsic CD, but high optical chirality and electric field enhancements in the near-fields. Owing to its unique set of properties, this configuration enables us to directly differentiate phenylalanine enantiomers in the visible frequency range.

  • 5.
    Gu, C.
    et al.
    China.
    Chi, X.
    China.
    Cheng, Y.
    China.
    Zichi, Julien
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Hu, N.
    China.
    Lan, X.
    Chona.
    Zou, K.
    China.
    Chen, S.
    China.
    Lin, Z.
    China.
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Hu, X.
    China.
    Fractal superconducting nanowire single-photon detectors with low polarization sensitivity2018In: Optics InfoBase Conference Papers, Optical Society of America, 2018Conference paper (Refereed)
    Abstract [en]

    We demonstrated a fractal superconducting nanowire single-photon detector and achieved 42% device efficiency and 1.04 polarization sensitivity. The low polarization sensitivity can be maintained for higher-order spatial modes in few-mode optical fibers.

  • 6. Gu, C.
    et al.
    Chi, X.
    Cheng, Y.
    Zichi, Julien
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Hu, N.
    Lan, X.
    Zou, K.
    Chen, S.
    Lin, Zuzeng
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Hu, X.
    Fractal superconducting nanowire single-photon detectors with low polarization sensitivity2018In: 2018 Conference on Lasers and Electro-Optics, CLEO 2018 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018, article id 8426796Conference paper (Refereed)
    Abstract [en]

    We demonstrated a fractal superconducting nanowire single-photon detector and achieved 42% device efficiency and 1.04 polarization sensitivity. The low polarization sensitivity can be maintained for higher-order spatial modes in few-mode optical fibers.

  • 7. Huang, Bingru
    et al.
    Bergstrand, Jan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Duan, Sai
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Zhan, Qiuqiang
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Ågren, Hans
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Liu, Haichun
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Overtone Vibrational Transition-InducedLanthanide Excited-State Quenching in Yb3+/Er3+-Doped Upconversion Nanocrystals2018In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, p. 10572-10575Article in journal (Refereed)
  • 8.
    Jöns, Klaus D.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Schweickert, Lucas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Versteegh, Marijn A. M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Dalacu, D.
    Poole, P. J.
    Gulinatti, A.
    Giudice, A.
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Reimer, M. E.
    Erratum to: Bright nanoscale source of deterministic entangled photon pairs violating Bell’s inequality (Scientific Reports, (2017), 7, 1, (1700), 10.1038/s41598-017-01509-6)2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, no 1, article id 7751Article in journal (Refereed)
  • 9.
    Mukhtarova, Anna
    et al.
    Univ Grenoble Alpes, CEA, INAC, PHELIQS, 17 Av Martyrs, F-38000 Grenoble, France..
    Redaelli, Luca
    Univ Grenoble Alpes, CEA, INAC, PHELIQS, 17 Av Martyrs, F-38000 Grenoble, France..
    Hazra, Dibyendu
    Univ Grenoble Alpes, CEA, INAC, PHELIQS, 17 Av Martyrs, F-38000 Grenoble, France..
    Machhadani, Houssaine
    Univ Grenoble Alpes, CEA, INAC, PHELIQS, 17 Av Martyrs, F-38000 Grenoble, France..
    Lequien, Stephane
    Univ Grenoble Alpes, CEA, INAC, MEM, 17 Av Martyrs, F-38000 Grenoble, France..
    Hofheinz, Max
    Univ Grenoble Alpes, CEA, INAC, PHELIQS, 17 Av Martyrs, F-38000 Grenoble, France..
    Thomassin, Jean-Luc
    Univ Grenoble Alpes, CEA, INAC, PHELIQS, 17 Av Martyrs, F-38000 Grenoble, France..
    Gustavo, Frederic
    Univ Grenoble Alpes, CEA, INAC, PHELIQS, 17 Av Martyrs, F-38000 Grenoble, France..
    Zichi, Julien
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics. Univ Grenoble Alpes, CEA, INAC, PHELIQS, 17 Av Martyrs, F-38000 Grenoble, France.;Delft Univ Technol, Kavli Inst Nanosci, Lorentzweig 1, NL-2628 CJ Delft, Netherlands..
    Monroy, Eva
    Univ Grenoble Alpes, CEA, INAC, PHELIQS, 17 Av Martyrs, F-38000 Grenoble, France..
    Gerard, Jean-Michel
    Univ Grenoble Alpes, CEA, INAC, PHELIQS, 17 Av Martyrs, F-38000 Grenoble, France..
    Polarization-insensitive fiber-coupled superconducting-nanowire single photon detector using a high-index dielectric capping layer2018In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 26, no 13, p. 17697-17704Article in journal (Refereed)
    Abstract [en]

    Superconducting-nanowire single photon detectors (SNSPDs) are able to reach near-unity detection efficiency in the infrared spectral range. However, due to the intrinsic asymmetry of nanowires, SNSPDs are usually very sensitive to the polarization of the incident radiation, their responsivity being maximum for light polarized parallel to the nanowire length (transverse-electric (TE) polarization). Here, we report on the reduction of the polarization sensitivity obtained by capping NbN-based SNSPDs with a high-index SiNx dielectric layer, which reduces the permittivity mismatch between the NbN wire and the surrounding area. Experimentally, a polarization sensitivity below 0.1 is obtained both at 1.31 and 1.55 mu m, in excellent agreement with simulations.

  • 10. Neumayer, Sabine M.
    et al.
    Ievlev, Anton V.
    Collins, Liam
    Vasudevan, Rama
    Baghban, Mohammad Amin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Ovchinnikova, Olga
    Jesse, Stephen
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics. KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Rodriguez, Brian J.
    Kalinin, Sergei V.
    Surface Chemistry Controls Anomalous Ferroelectric Behavior in Lithium Niobate2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 34, p. 29153-29160Article in journal (Refereed)
    Abstract [en]

    Polarization switching in ferroelectric materials underpins a multitude of applications ranging from nonvolatile memories to data storage to ferroelectric lithography. While traditionally considered to be a functionality of the material only, basic theoretical considerations suggest that switching is expected to be intrinsically linked to changes in the electrochemical state of the surface. Hence, the properties and dynamics of the screening charges can affect or control the switching dynamics. Despite being recognized for over 50 years, analysis of these phenomena remained largely speculative. Here, we explore polarization switching on the prototypical LiNbO3 surface using the combination of contact mode Kelvin probe force microscopy and chemical imaging by time-of-flight mass-spectrometry and demonstrate pronounced chemical differences between the domains. These studies provide a consistent explanation to the anomalous polarization and surface charge behavior observed in LiNbO3 and point to new opportunities in chemical control of polarization dynamics in thin films and crystals via control of surface chemistry, complementing traditional routes via bulk doping, and substrate-induced strain and tilt systems.

  • 11.
    Pathak, Anuj
    et al.
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, SE-17177 Stockholm, Sweden..
    Bergstrand, Jan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Sender, Vicky
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, SE-17177 Stockholm, Sweden..
    Spelmink, Laura
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, SE-17177 Stockholm, Sweden..
    Aschtgen, Marie-Stephanie
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, SE-17177 Stockholm, Sweden..
    Muschiol, Sandra
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, SE-17177 Stockholm, Sweden..
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Henriques-Normark, Birgitta
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, SE-17177 Stockholm, Sweden.;Nanyang Technol Univ, Lee Kong Chian Sch Med LKC, Singapore 639798, Singapore.;Nanyang Technol Univ, Singapore Ctr Environm Life Sci Engn SCELSE, Singapore 639798, Singapore.;Karolinska Univ Hosp, Dept Clin Microbiol, SE-17176 Stockholm, Sweden..
    Factor H binding proteins protect division septa on encapsulated Streptococcus pneumoniae against complement C3b deposition and amplification2018In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 9, article id 3398Article in journal (Refereed)
    Abstract [en]

    Streptococcus pneumoniae evades C3-mediated opsonization and effector functions by expressing an immuno-protective polysaccharide capsule and Factor H (FH)-binding proteins. Here we use super-resolution microscopy, mutants and functional analysis to show how these two defense mechanisms are functionally and spatially coordinated on the bacterial cell surface. We show that the pneumococcal capsule is less abundant at the cell wall septum, providing C3/C3b entry to underlying nucleophilic targets. Evasion of C3b deposition at division septa and lateral amplification underneath the capsule requires localization of the FH-binding protein PspC at division sites. Most pneumococcal strains have one PspC protein, but successful lineages in colonization and disease may have two, PspC1 and PspC2, that we show affect virulence differently. We find that spatial localization of these FH-recruiting proteins relative to division septa and capsular layer is instrumental for pneumococci to resist complement-mediated opsonophagocytosis, formation of membrane-attack complexes, and for the function as adhesins.

  • 12.
    Schollhammer, Jean
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Baghban, Mohammad Amin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Birefringence-free lithium niobate waveguides2017In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2017Conference paper (Refereed)
  • 13.
    Schweickert, Lucas
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Jöns, Klaus D.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Zeuner, Katharina D.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    da Silva, Saimon Filipe Covre
    Huang, Huiying
    Lettner, Thomas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Reindl, Marcus
    Zichi, Julien
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Trotta, Rinaldo
    Rastelli, Armando
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    On-demand generation of background-free single photons from a solid-state source2018In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, no 9, article id 093106Article in journal (Refereed)
    Abstract [en]

    True on-demand high-repetition-rate single-photon sources are highly sought after for quantum information processing applications. However, any coherently driven two-level quantum system suffers from a finite re-excitation probability under pulsed excitation, causing undesirable multi-photon emission. Here, we present a solid-state source of on-demand single photons yielding a raw second-order coherence of g((2)) (0) = (7.5 +/- 1.6) x 10(-5) without any background subtraction or data processing. To this date, this is the lowest value of g((2)) (0) Peported for any single-photon source even compared to the previously reported best background subtracted values. We achieve this result on GaAs/AlGaAs quantum dots embedded in a low-Q planar cavity by employing (i) a two-photon excitation process and (ii) a filtering and detection setup featuring two superconducting single-photon detectors with ultralow dark-count rates of (0.0056 +/- 0.0007) s(-1) and (0.017 +/- 0.001) s(-1), respectively. Re-excitation processes are dramatically suppressed by (i), while (ii) removes false coincidences resulting in a negligibly low noise floor.

  • 14.
    Stensson, Katarina
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Björk, Gunnar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Measurement of the two-time intensity-correlation function of arbitrary statesManuscript (preprint) (Other academic)
    Abstract [en]

    For light intensity correlations measurements, different methods are used in the high photon number or high intensity regime and in the single- and two-photon regime. Hence, there is an unfortunate measurement ``gap’’ primarily for multi-photon, quantum states. These states, for example multi-photon Fock states will be increasingly important in the realization of quantum technologies and in exploring the boundaries between quantum and classical optics. We show that a na\"{i}ve approach, based on attenuation, state splitting, and two-detector correlation, can give the correct two-time intensity correlation for any state. We analyze how added losses decrease the measurement’s systematic error. The price to be paid is that the losses increase the measurement statistical error or alternatively, increases the acquisition time for a given tolerable level of statistical error. We have experimentally demonstrated the feasibility of the method for a coherent state and a quasi-thermal state. The method is easy to implement in any laboratory and will simplify characterization of medium and highly excited non-classical states as they become experimentally available.

  • 15.
    Tornmalm, Johan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Label-free monitoring of ambient oxygenation and redox conditions using the photodynamics of flavin compounds and transient state (TRAST) spectroscopy2018In: Methods, ISSN 1046-2023, E-ISSN 1095-9130, Vol. 140, p. 178-187Article in journal (Refereed)
    Abstract [en]

    Transient state (TRAST) monitoring can determine population dynamics of long-lived, dark transient states of fluorescent molecules, detecting only the average fluorescence intensity from a sample, when subject to different excitation pulse trains. Like Fluorescence Correlation Spectroscopy (FCS), TRAST unites the detection sensitivity of fluorescence with the environmental sensitivity of long-lived non-fluorescent states, but does not rely on detection of stochastic fluorescence fluctuations from individual molecules. Relaxed requirements on noise suppression, detection quantum yield and time-resolution of the instrument, as well as on fluorescence brightness of the molecules studied, make TRAST broadly applicable, opening also for investigations based on less bright, auto-fluorescent molecules. In this work, we applied TRAST to study the transient state population dynamics within the auto-fluorescent coenzymes flavin adenine dinucleotide (FAD) and flavin-mononucleotide (FMN). From the experimental TRAST data, we defined state models, and determined rate parameters for triplet state and redox transitions within FMN and FAD, stacking and un-stacking rates of external redox active quenching agents and by the adenine moiety of FAD itself. TRAST experiments were found to be well capable to resolve these transitions in FMN and FAD, and to track how the transitions are influenced by ambient oxygenation and redox conditions. This work demonstrates that TRAST provides a useful tool to follow local oxygenation and redox conditions via FMN and FAD fluorescence, and forms the basis for measurements on flavoproteins and of redox and metabolic conditions in more complex environments, such as in live cells.

  • 16.
    Xu, Lei
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics.
    Braun, Laura J.
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, Stockholm, Sweden..
    Rönnlund, Daniel
    KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics.
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Aspenstrom, Pontus
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, Stockholm, Sweden..
    Gad, Annica K. B.
    Univ Madeira, CQM, Campus Penteada, P-9020105 Funchal, Portugal..
    Nanoscale localization of proteins within focal adhesions indicates discrete functional assemblies with selective force-dependence2018In: The FEBS Journal, ISSN 1742-464X, E-ISSN 1742-4658, Vol. 285, no 9, p. 1635-1652Article in journal (Refereed)
    Abstract [en]

    Focal adhesions (FAs) are subcellular regions at the micrometer scale that link the cell to the surrounding microenvironment and control vital cell functions. However, the spatial architecture of FAs remains unclear at the nanometer scale. We used two-color and three-color super-resolution stimulated emission depletion microscopy to determine the spatial distributions and co-localization of endogenous FA components in fibroblasts. Our data indicate that adhesion proteins inside, but not outside, FAs are organized into nanometer size units of multi-protein assemblies. The loss of contractile force reduced the nanoscale co-localization between different types of proteins, while it increased this co-localization between markers of the same type. This suggests that actomyosin-dependent force exerts a nonrandom, specific, control of the localization of adhesion proteins within cell-matrix adhesions. These observations are consistent with the possibility that proteins in cell-matrix adhesions are assembled in nanoscale particles, and that force regulates the localization of the proteins therein in a protein-specific manner. This detailed knowledge of how the organization of FA components at the nanometer scale is linked to the capacity of the cells to generate contractile forces expands our understanding of cell adhesion in health and disease.

1 - 16 of 16
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf