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  • 1.
    Al-attar, N.
    et al.
    Iraq.
    Al-Shammari, R. M.
    Ireland.
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Rodriguez, B. J.
    Ireland.
    Rice, J. H.
    Ireland.
    Wide-field surface-enhanced Raman scattering from ferroelectrically defined Au nanoparticle microarrays for optical sensing2018In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2018Conference paper (Refereed)
    Abstract [en]

    The acquisition-time in optical sensors using SERS is vital value. Wide-field SERS is used to perform high-density of hot-spots of GNPs photodeposition on a periodically-protonexchanged- LiNbO3 which, leads to increase the sensitivity at ultralow probe concentrations.

  • 2.
    Asadzadeh, Mohammad Zhian
    et al.
    Mat Ctr Leoben Forsch GmbH MCL, Roseggerstr 12, A-8700 Leoben, Austria..
    Kock, Anton
    Mat Ctr Leoben Forsch GmbH MCL, Roseggerstr 12, A-8700 Leoben, Austria..
    Popov, Maxim
    Mat Ctr Leoben Forsch GmbH MCL, Roseggerstr 12, A-8700 Leoben, Austria..
    Steinhauer, Stephan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics. Mat Ctr Leoben Forsch GmbH MCL, Roseggerstr 12, A-8700 Leoben, Austria.
    Spitaler, Juergen
    Mat Ctr Leoben Forsch GmbH MCL, Roseggerstr 12, A-8700 Leoben, Austria..
    Romaner, Lorenz
    Mat Ctr Leoben Forsch GmbH MCL, Roseggerstr 12, A-8700 Leoben, Austria..
    Response modeling of single SnO2 nanowire gas sensors2019In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 295, p. 22-29Article in journal (Refereed)
    Abstract [en]

    The response of single SnO2 nanowire gas sensors with different diameters between 20 and 140 nm are evaluated by calculating the nanowire conductivity as a function of the surface charge density. The procedure involves the numerical solution of the Poisson-Boltzmann equation for the electrostatic potential in cylindrical geometry in order to model the depletion region and band bending at the SnO2 nanowire surface. In the model we take into account varying surface charge densities sigma and bulk electron concentrations n(0) to calculate the electrical conductivity. Considering the fact that the surface charge density depends on the nanowire surface interactions with ambient gas, the model allows us to simulate the sensor response when the nanowire is employed as gas sensing component. We report a saturation in depletion length lambda versus surface charge density s which is the principal reason for limiting the sensor responses. The results also show that the conductivity is decreasing by increasing surface charge density, the smaller the nanowire diameter the steeper the decrease. As a result the nanowire response is proportional to 1/d where d is the nanowire diameter. Furthermore, we argue about the validity of the modeling results and their relevance to experimental findings on SnO2 nanowire based gas sensors reported in literature.

  • 3.
    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.

  • 4.
    Baghban, Mohammad Amin
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Phase-Shifted Bragg Grating Resonators in Thin-Film Lithium Niobate Waveguides2019In: 2019 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), 2019Conference paper (Refereed)
    Abstract [en]

    We demonstrate narrowband integrated filters with 0.23 mm-long phase-shifted Bragg gratings in corrugated single-mode thin-film LiNbO3 photonic wires, achieving quality factors of 1.24x10(4) and extinction ratios up to 24 dB at telecom wavelengths.

  • 5.
    Baghban, Mohammad Amin
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Schollhammer, Jean
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Errando-Herranz, Carlos
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Gylfason, Kristinn B
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Bragg gratings in thin-film LiNbO3 waveguides2017In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Optics Express, ISSN 1094-4087, Vol. 25, no 26, p. 32323-32332Article in journal (Refereed)
    Abstract [en]

    We design, fabricate and characterize sidewall corrugated Bragg gratings in a high confinement integrated optics lithium niobate platform, comprising submicrometric photonic wires, tapers and grating couplers to interface off-chip standard telecom optical fibers. We analyze the grating performance as band-rejection filter for TE-polarized signals in the telecom C-band, considering both rectangular and sinusoidal sidewall profiles, and demonstrate record extinction ratios as high as 27 dB and rejection bandwidths as narrow as 3 nm. The results show the potential for an efficient integration of novel photonic functionalities into low-footprint LiNbO3 nonlinear and electro-optical waveguide devices.

  • 6.
    Baghban, Mohammad Amin
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Swillo, Marcin
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Second-Harmonic generation engineering in lithium niobate nanopillars2019In: Proceedings 2015 European Conference on Lasers and Electro-Optics - European Quantum Electronics Conference, CLEO/Europe-EQEC 2015, Optical Society of America (OSA) , 2019Conference paper (Refereed)
  • 7.
    Bagheri, Shervin
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Mechanics, Stability, Transition and Control. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Liu, Q.ingyun
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Bergstrand, Jan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Pu, R.
    Centre for Optical and Electromagnetic Research, Guangdong Provincial Key Laboratory of Optical Information.
    Zhan, Q.
    Centre for Optical and Electromagnetic Research, Guangdong Provincial Key Laboratory of Optical Information.
    Ara, M. H. M.
    Photonics Laboratory, Physics Department, Kharazmi University, Tehran, Iran.
    Ågren, Hans
    KTH, Superseded Departments (pre-2005), Biotechnology. KTH, Superseded Departments (pre-2005), Chemistry. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova. 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.
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Change in the emission saturation and kinetics of upconversion nanoparticles under different light irradiations2019In: Optical materials (Amsterdam), ISSN 0925-3467, E-ISSN 1873-1252, Vol. 97, article id 109389Article in journal (Refereed)
    Abstract [en]

    Nd3+-sensitized upconversion nanoparticles (UCNPs) can be excited by both 980 and 808 nm light, which is regarded as a particularly advantageous property of these particles. In this work, we demonstrate that the nanoparticles can exhibit significantly different response when excited at these two excitation wavelengths, showing dependence on the intensity of the excitation light and the way it is distributed in time. Specifically, with 808 nm excitation saturation in the emitted luminescence is more readily reached with increasing excitation intensities than upon 980 nm excitation. This is accompanied by delayed upconversion luminescence (UCL) kinetics and weaker UCL intensities. The different luminescence response at 808 and 980 nm excitation reported in this work is relevant in a manifold of applications using UCNPs as labels and sensors. This could also open new possibilities for multi-wavelength excitable UCNPs for upconversion color display and in laser-scanning microscopy providing selective readouts and sub-sectioning of samples.

  • 8.
    Basset, F. Basso
    et al.
    Sapienza Univ Rome, Dept Phys, I-00185 Rome, Italy..
    Rota, M. B.
    Sapienza Univ Rome, Dept Phys, I-00185 Rome, Italy..
    Schimpf, C.
    Johannes Kepler Univ Linz, Inst Semicond & Solid State Phys, A-4040 Linz, Austria..
    Tedeschi, D.
    Sapienza Univ Rome, Dept Phys, I-00185 Rome, Italy..
    Zeuner, Katharina
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    da Silva, S. F. Covre
    Johannes Kepler Univ Linz, Inst Semicond & Solid State Phys, A-4040 Linz, Austria..
    Reindl, M.
    Johannes Kepler Univ Linz, Inst Semicond & Solid State Phys, A-4040 Linz, Austria..
    Zwiller, Val
    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.
    Rastelli, A.
    Johannes Kepler Univ Linz, Inst Semicond & Solid State Phys, A-4040 Linz, Austria..
    Trotta, R.
    Sapienza Univ Rome, Dept Phys, I-00185 Rome, Italy..
    Entanglement Swapping with Photons Generated on Demand by a Quantum Dot2019In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 123, no 16, article id 160501Article in journal (Refereed)
    Abstract [en]

    Photonic entanglement swapping, the procedure of entangling photons without any direct interaction, is a fundamental test of quantum mechanics and an essential resource to the realization of quantum networks. Probabilistic sources of nonclassical light were used for seminal demonstration of entanglement swapping, but applications in quantum technologies demand push-button operation requiring single quantum emitters. This, however, turned out to be an extraordinary challenge due to the stringent prerequisites on the efficiency and purity of the generation of entangled states. Here we show a proof-of-concept demonstration of all-photonic entanglement swapping with pairs of polarization-entangled photons generated on demand by a GaAs quantum dot without spectral and temporal filtering. Moreover, we develop a theoretical model that quantitatively reproduces the experimental data and provides insights on the critical figures of merit for the performance of the swapping operation. Our theoretical analysis also indicates how to improve stateof-the-art entangled-photon sources to meet the requirements needed for implementation of quantum dots in long-distance quantum communication protocols.

  • 9.
    Bergstrand, Jan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Super resolution fluorescence imaging: analyses, simulations and applications2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fluorescence methods offer extraordinary sensitivity and specificity, and are extensively used in the life sciences. In recent years, super resolution fluorescence imaging techniques have developed strongly, uniquely combining ~10 nm sub diffraction resolution and specific labeling with high efficiency. This thesis explores this potential, with a major focus on Stimulated Emission Depletion, STED, microscopy, applications thereof, image analyses and simulation studies. An additional theme in this thesis is development and use of single molecule fluorescence correlation spectroscopy, FCS, and related techniques, as tools to study dynamic processes at the molecular level. In paper I the proteins cytochrome-bo3 and ATP-synthase are studied with fluorescence cross-correlation spectroscopy, FCCS. These two proteins are a part of the energy conversion process in E. coli, converting ADP into ATP. We found that an increased interaction between these proteins, detected by FCCS, correlates with an increase in the ATP production. In paper II an FCS-based imaging method is developed, capable to determine absolute sizes of objects, smaller than the resolution limit of the microscope used. Combined with STED, this may open for studies of membrane nano-domains, such as those investigated by simulations in paper VII. In paper III and paper IV super resolution STED imaging was applied on Streptococcus Pneumoniae, revealing information about function and distribution of proteins involved in the defense mechanism of the bacteria, as well as their role in bacterial meningitis. In paper V, we used STED imaging to investigate protein distributions in platelets. We then found that the adhesion protein P-selectin changes its distribution pattern in platelets incubated with tumor cells, and with machine learning algorithms and classical image analysis of the STED images it is possible to automatically distinguish such platelets from platelets activated by other means. This could provide a strategy for minimally invasive diagnostics of early cancer development, and deeper understanding of the role of platelets in cancer development. Finally, this thesis presents Monte-Carlo simulations of biological processes and their monitoring by FCS. In paper VI, a combination of FCCS and simulations was applied to resolve the interactions between a transcription factor (p53) and an oncoprotein (MDM2) inside live cells. In paper VII, the feasibility of FCS techniques for studying nano-domains in membranes is investigated purely by simulations, identifying the conditions under which such nano-domains would be possible to detect by FCS. In paper VIII, proton exchange dynamics at biological membranes were simulated in a model, verifying experimental FCS data and identifying fundamental mechanisms by which membranes mediate proton exchange on a local (~10nm) scale.

  • 10.
    Bergstrand, Jan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Liu, Qingyun
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Huang, Bingru
    Würth, Christian
    Resch-Genger, Ute
    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.
    On the decay time of upconversion luminescence2019In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, no 11, p. 4959-4969Article in journal (Refereed)
    Abstract [en]

    In this study, we systematically investigate the decay characteristics of upconversion luminescence (UCL) under anti-Stokes excitation through numerical simulations based on rate-equation models. We find that a UCL decay profile generally involves contributions from the sensitizer's excited-state lifetime, energy transfer and cross-relaxation processes. It should thus be regarded as the overall temporal response of the whole upconversion system to the excitation function rather than the intrinsic lifetime of the luminescence emitting state. Only under certain conditions, such as when the effective lifetime of the sensitizer's excited state is significantly shorter than that of the UCL emitting state and of the absence of cross-relaxation processes involving the emitting energy level, the UCL decay time approaches the intrinsic lifetime of the emitting state. Subsequently, Stokes excitation is generally preferred in order to accurately quantify the intrinsic lifetime of the emitting state. However, possible cross-relaxation between doped ions at high doping levels can complicate the decay characteristics of the luminescence and even make the Stokes-excitation approach fail. A strong cross-relaxation process can also account for the power dependence of the decay characteristics of UCL.

  • 11.
    Bergstrand, Jan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Xu, Lei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics. Royal Inst Technol KTH, Dept Appl Phys, Albanova Univ Ctr, Expt Biomol Phys, SE-10691 Stockholm, Sweden..
    Miao, Xinyan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics. Royal Inst Technol KTH, Dept Appl Phys, Albanova Univ Ctr, Expt Biomol Phys, SE-10691 Stockholm, Sweden..
    Li, Nailin
    Karolinska Inst, Dept Med Solna, Karolinska Univ Hosp Solna, Clin Pharmacol, L7 03, SE-17176 Stockholm, Sweden..
    Öktem, Ozan
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    Franzen, Bo
    Karolinska Inst, Dept Oncol Pathol, Karolinska Univ Hosp, K7,Z1 00, S-17176 Stockholm, Sweden..
    Auer, Gert
    Karolinska Inst, Dept Oncol Pathol, Karolinska Univ Hosp, K7,Z1 00, S-17176 Stockholm, Sweden..
    Lomnytska, Marta
    Karolinska Inst, Dept Oncol Pathol, Karolinska Univ Hosp, K7,Z1 00, S-17176 Stockholm, Sweden.;Acad Univ Hosp, Dept Obstet & Gynaecol, SE-75185 Uppsala, Sweden.;Uppsala Univ, Inst Women & Child Hlth, SE-75185 Uppsala, Sweden..
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Super-resolution microscopy can identify specific protein distribution patterns in platelets incubated with cancer cells2019In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, no 20, p. 10023-10033Article in journal (Refereed)
    Abstract [en]

    Protein contents in platelets are frequently changed upon tumor development and metastasis. However, how cancer cells can influence protein-selective redistribution and release within platelets, thereby promoting tumor development, remains largely elusive. With fluorescence-based super-resolution stimulated emission depletion (STED) imaging we reveal how specific proteins, implicated in tumor progression and metastasis, re-distribute within platelets, when subject to soluble activators (thrombin, adenosine diphosphate and thromboxane A2), and when incubated with cancer (MCF-7, MDA-MB-231, EFO21) or non-cancer cells (184A1, MCF10A). Upon cancer cell incubation, the cell-adhesion protein P-selectin was found to re-distribute into circular nano-structures, consistent with accumulation into the membrane of protein-storing alpha-granules within the platelets. These changes were to a significantly lesser extent, if at all, found in platelets incubated with normal cells, or in platelets subject to soluble platelet activators. From these patterns, we developed a classification procedure, whereby platelets exposed to cancer cells, to non-cancer cells, soluble activators, as well as non-activated platelets all could be identified in an automatic, objective manner. We demonstrate that STED imaging, in contrast to electron and confocal microscopy, has the necessary spatial resolution and labelling efficiency to identify protein distribution patterns in platelets and can resolve how they specifically change upon different activations. Combined with image analyses of specific protein distribution patterns within the platelets, STED imaging can thus have a role in future platelet-based cancer diagnostics and therapeutic monitoring. The presented approach can also bring further clarity into fundamental mechanisms for cancer cell-platelet interactions, and into non-contact cell-to-cell interactions in general.

  • 12.
    Bergstrand, Jan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Xu, Lei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Miao, Xinyan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Li, Nailin
    Karolinska Institutet, Department of Medicine, Karolinska University Hospital, L7:03, SE-171 76 Stockholm, Sweden.
    Öktem, Ozan
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    Franzén, Bo
    Karolinska Institutet, Department of Medicine, Karolinska University Hospital, L7:03, SE-171 76 Stockholm, Sweden.
    Auer, Gert
    Karolinska Institutet, Department of Medicine, Karolinska University Hospital, L7:03, SE-171 76 Stockholm, Sweden.
    Lomnytska, Marta
    Karolinska Institutet, Department of Medicine, Karolinska University Hospital, L7:03, SE-171 76 Stockholm, Sweden.
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Super-resolution microscopy can identify specific protein distribution patterns in platelets incubated with cancer cellsManuscript (preprint) (Other academic)
    Abstract [en]

    Protein contents in platelets are frequently changed upon tumor development and metastasis. However, how cancer cells can influence protein-selective redistribution and release within platelets, thereby promoting tumor development, remains largely elusive. With fluorescence-based super-resolution stimulated emission depletion (STED) imaging we reveal how specific proteins, implicated in tumor progression and metastasis, re-distribute within platelets, when subject to soluble activators (thrombin, adenosine-diphosphate and thromboxaneA2), and when incubated with cancer (MCF-7, MDA-MB-231, EFO21) or non-cancer cells (184A1, MCF10A). Upon cancer cell incubation, the cell-adhesion protein P-selectin was found to re-distribute into circular nano-structures, consistent with accumulation into the membrane of protein-storing alpha-granules within the platelets. These changes were to a significantly lesser extent, if at all, found in platelets incubated with normal cells, or in platelets subject to soluble platelet activators. From these patterns, we developed a classification procedure, whereby platelets exposed to cancer cells, to non-cancer cells, soluble activators as well as non-activated platelets all could be identified in an automatic, objective manner. We demonstrate that STED imaging, in contrast to electron and confocal microscopy, has the necessary spatial resolution and labelling efficiency to identify protein distribution patterns in platelets and can resolve how they specifically change upon different activations. Combined with image analyses of specific protein distribution patterns within the platelets, STED imaging can thus have a role in future platelet-based cancer diagnostics and therapeutic monitoring. The presented approach can also bring further clarity into fundamental mechanisms for cancer cell-platelet interactions, and into non-contact cell-to-cell interactions in general. 

  • 13.
    Brambilla, E.
    et al.
    Univ Insubria, Dept Sci & High Technol, Via Valleggio 11, I-22100 Como, Italy..
    Jedrkiewicz, O.
    CNR, Ist Foton & Nanotecnol, Udr Como, Via Valleggio 11, I-22100 Como, Italy..
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Tamosauskas, G.
    Vilnius Univ, Dept Quantum Elect, Sauletekio 10, LT-10223 Vilnius, Lithuania..
    Gatti, A.
    CNR, Ist Foton & Nanotecnol, Udr Como, Via Valleggio 11, I-22100 Como, Italy..
    Three and Four-Modes Parametric Processes in Hexagonally Poled Nonlinear Photonic Crystals2018In: OPTICS, PHOTONICS AND LASERS / [ed] Yurish, S Y, INT FREQUENCY SENSOR ASSOC-IFSA , 2018, p. 176-178Conference paper (Refereed)
    Abstract [en]

    We investigate the properties of the field emitted through parametric down-conversion (PDC) in a nonlinear photonics crystal (NPC) with a hexagonal poling pattern, both from a theoretical point of view and with an experiment performed at the University of Insubria. Considering the high gain regime of PDC, we demonstrate the existence of concurrent PDC processes mediated by two noncollinear poling vectors which are coherently coupled and reciprocally stimulated. We find that these non-standard 3-mode and 4-mode interaction processes undergo a substantial enhancement of the parametric gain with respect to the usual 2-mode PDC, and give rise to hot spots order of magnitudes brighter than standard 2-mode fluorescence which have been observed in the source far field. We performed a complete characterization of the source spectral-angular emission, finding a very good agreement between the experiment and the theoretical predictions.

  • 14.
    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.

  • 15. Cheng, Y.
    et al.
    Chi, X.
    Gu, C.
    Zou, K.
    Zichi, Julien
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Chen, S.
    Liu, H.
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Hu, X.
    Experimental demonstration of superconducting nanowire single-photon detectors integrated with current reservoirs2018In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2018Conference paper (Refereed)
    Abstract [en]

    We experimentally demonstrate the superconducting nanowire single-photon detectors integrated with current reservoirs that function as low-noise pre-amplifiers to increase the signal-to-noise ratio of detectors' outputs.

  • 16.
    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.

  • 17.
    Datta, Abheek
    et al.
    Okinawa Inst Sci & Technol OIST Grad Univ, Nanoparticles Design Unit, 1919-1 Tancha, Onna Son, Okinawa 9040495, Japan..
    Porkovich, Alexander J.
    Okinawa Inst Sci & Technol OIST Grad Univ, Nanoparticles Design Unit, 1919-1 Tancha, Onna Son, Okinawa 9040495, Japan..
    Kumar, Pawan
    Okinawa Inst Sci & Technol OIST Grad Univ, Nanoparticles Design Unit, 1919-1 Tancha, Onna Son, Okinawa 9040495, Japan..
    Nikoulis, Giorgos
    Aristotle Univ Thessaloniki, Dept Phys, GR-54124 Thessaloniki, Greece..
    Kioseoglou, Joseph
    Aristotle Univ Thessaloniki, Dept Phys, GR-54124 Thessaloniki, Greece..
    Sasaki, Toshio
    Okinawa Inst Sci & Technol OIST Grad Univ, Imaging Sect, 1919-1 Tancha, Onna Son, Okinawa 9040495, Japan..
    Steinhauer, Stephan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Grammatikopoulos, Panagiotis
    Okinawa Inst Sci & Technol OIST Grad Univ, Nanoparticles Design Unit, 1919-1 Tancha, Onna Son, Okinawa 9040495, Japan..
    Sowwan, Mukhles
    Okinawa Inst Sci & Technol OIST Grad Univ, Nanoparticles Design Unit, 1919-1 Tancha, Onna Son, Okinawa 9040495, Japan..
    Single Nanoparticle Activities in Ensemble: A Study on Pd Cluster Nanoportals for Electrochemical Oxygen Evolution Reaction2019In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 43, p. 26124-26135Article in journal (Refereed)
    Abstract [en]

    Comprehensive understanding of the electrochemical activity of single nanoparticles (NPs) is in critical need for opening new avenues in the broad field of electrochemistry. Published reports on single-NP electrocatalysts typically include complicated and difficult methods of synthesis and characterization; moreover, these methods usually fail to provide a reliable way to measure the activities of individual NPs within larger ensembles of particles, i.e., in real-life nanocatalyst systems. In the present work, we synthesized from the gas phase Pd NPs that act as nanoportals for electron transfer within surface-oxidized Mg thin films. The physical synthesis method provided excellent control over the deposition density and, hence, enabled the design of a system where each individual open nanoportal forms an independent active single-NP electrode (SNPE). Being uncoupled from one another, these SNPEs contribute separately toward the total electrocatalytic activity while simultaneously providing a measure of their average, individual activities. We were thus able to fabricate a stable, steady-state electrode for the electrochemical oxygen evolution reaction (OER) and to study the activity and stability of the SNPEs over a period of 20 days; the former depended on the size of the NPs, while the latter depended on the SNPEs' resistance to aerial oxidation. The remarkable stability of the ensemble catalysts under OER conditions proves that this concept can be used for further studies on the activities of different single NPs in numerous real-life systems.

  • 18.
    De Luca, Eleonora
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Nonlinear Properties of III-V Semiconductor Nanowaveguides2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nonlinear optics (NLO) plays a major role in the modern world: nonlinear optical phenomena have been observed in a wavelength range going from the deep infrared to the extreme ultraviolet, to THz radiation. The optical nonlinearities can be found in crystals, amorphous materials, polymers, liquid crystals, liquids, organic materials, and even gases and plasmas. Nowadays, NLO is relevant for applications in quantum optics, quantum computing, ultra-cold atom physics, plasma physics, and particle accelerators. The work presented in the thesis is limited only to the semiconductors that have a second-order optical nonlinearity and includes two phenomena that use second-order nonlinearity: second-harmonic generation (SHG) and spontaneous parametric down-conversion (SPDC). Among the many options available, the investigation presented concerns gallium phosphide (GaP) and gallium indium phosphide (Ga0.51In0.49P), two semiconductors of the group III-V with the ¯43m crystal symmetry.

    However, some of the results found can be generalized for other materials with ¯43m crystal symmetry.

    In the thesis, the fabrication of GaP nanowaveguides with dimensions from 0.03 μm and an aspect ratio above 20 using focused ion beam (FIB) milling is discussed. The problem of the formation of gallium droplets on the surface is solved by using a pulsed laser to oxidize the excess surface gallium locally on the FIB-milled nanowaveguides. SHG is used to evaluate the optical quality of the fabricated GaP nanowaveguides. Additionally, a theoretical and experimental way to enhance SHG in nanowaveguides is introduced. This process uses the overlap of interacting fields defined by the fundamental mode of the pump and the second-order mode of the SHG, which is enhanced by the longitudinal component of the nonlinear polarization density. Through this method, it was possible to obtain a maximum efficiency of 10−4, which corresponds to 50 W−1cm−2. The method can be generalized for any material with a ¯43m crystal symmetry. Furthermore, SHG is used to characterize the nonlinear properties of a nanostructure exposed for a long time to a CW laser at 405 nm to reduce the photoluminescence (PL) of Ga0.51In0.49P. The PL was reduced by -34 dB without causing any damage to the nanostructures or modifying the nonlinear properties. The fabrication process for obtaining the nanowaveguide is interesting as well, since the fabricated waveguide in Ga0.51In0.49P, whose sizes are 200 nm thick, 11 μm wide and 1.5 mm long, was transferred on silicon dioxide (SiO2). This type of nanowaveguide is interesting for SPDC, since it satisfies the long interaction length necessary for an efficient SPDC. Finally, a configuration consisting of illuminating the top surface of a nanowaveguide with a pump beam to generate signal and idler by SPDC is presented. These fabricated nanostructures open a way to the generation of counter-propagating idler and signal with orthogonal polarization. By using a different cut of the crystal, i.e. [110], it makes possible to obtain degenerate wavelength generation, and in certain conditions to obtain polarization-entangled photons or squeezed states.

  • 19.
    De Luca, Eleonora
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Swillo, Marcin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Degenerated Spontaneous Parametric Down Conversion in Semiconductor Waveguide with -43m Crystal SymmetryManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper, a configuration consisting in a pump propagating in an orthogonal direction with respect to the surface of a nanowaveguide is studied. It is possible to show that the generation by spontaneous parametric down-conversion of a signal and an idler photons inside the nanowaveguide is strongly dependent on the waveguide thickness, because the high refractive index of the waveguide core creates also an optical cavity for the pump field. Furthermore, it was evaluated the best condition for photon-pair generation in case of a nanowaveguide in gallium indium phosphide, which has a −43m symmetry.For the same waveguide geometry, but orientation parallel to the [110] plane, it is possible to use spontaneous parametric down-conversion to generate counter-propagating photon-pair with the same polarization. When the efficiency of the generated photon-pairs in TM0 and TE0 modes is the same, then it is possible to obtain polarization entangled photons, by using this configuration. Furthermore, by adding a mirror at one of the end of the waveguide, the system can be used to produce a squeezed-state.

  • 20.
    De Luca, Eleonora
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Visser, Dennis
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Anand, Srinivasan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Swillo, Marcin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Gallium Indium Phosphide Microstructures with Suppressed Photoluminescence for Applications in Nonlinear Optics2019In: Optics Letters, ISSN 0146-9592, Vol. 44, no 21Article in journal (Refereed)
    Abstract [en]

    Gallium indium phosphide (Ga0.51In0.49P), lattice matched to gallium arsenide, shows remarkable second-order nonlinear properties, as well as strong photoluminescence due to its direct band gap. By measuring the second-harmonic generation from the GaInP microwaveguide (0.2 x 11 x 1300 μm) before and after stimulating intrinsic photobleaching, we demonstrate that the photoluminescence could be strongly suppressed (-34 dB), leaving the nonlinear properties unchanged, making it suitable for low-noise applications.

  • 21.
    De Luca, Eleonora
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Visser, Dennis
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Anand, Srinivasan
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Swillo, Marcin
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gallium indium phosphide nanostructures with suppressed photoluminescence for applications in nonlinear optics2018In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2018Conference paper (Refereed)
    Abstract [en]

    Nanostructured GaInP shows remarkable second-order nonlinear properties. By measuring the second harmonic generation before and after stimulating intrinsic photobleaching, we observed suppressed photoluminescence and unchanged nonlinear properties, making it suitable for low-noise applications. 

  • 22.
    Elsinger, Lukas
    et al.
    Univ Ghent, IMEC, Photon Res Grp, B-9052 Ghent, Belgium.;Univ Ghent, NB Photon, B-9052 Ghent, Belgium..
    Gourgues, Ronan
    Single Quantum BV, NL-2628 CJ Delft, Netherlands..
    Zadeh, Iman E.
    Delft Univ Technol, Opt Res Grp, NL-2628 CJ Delft, Netherlands..
    Maes, Jorick
    Univ Ghent, NB Photon, B-9052 Ghent, Belgium.;Univ Ghent, Phys & Chem Nanostruct Grp, B-9000 Ghent, Belgium..
    Guardiani, Antonio
    Single Quantum BV, NL-2628 CJ Delft, Netherlands..
    Bulgarini, Gabriele
    Single Quantum BV, NL-2628 CJ Delft, Netherlands..
    Pereira, Silvania F.
    Delft Univ Technol, Opt Res Grp, NL-2628 CJ Delft, Netherlands..
    Dorenbos, Sander N.
    Single Quantum BV, NL-2628 CJ Delft, Netherlands..
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Hens, Zeger
    Univ Ghent, NB Photon, B-9052 Ghent, Belgium.;Univ Ghent, Phys & Chem Nanostruct Grp, B-9000 Ghent, Belgium..
    Van Thourhout, Dries
    Univ Ghent, IMEC, Photon Res Grp, B-9052 Ghent, Belgium.;Univ Ghent, NB Photon, B-9052 Ghent, Belgium..
    Integration of Colloidal PbS/CdS Quantum Dots with Plasmonic Antennas and Superconducting Detectors on a Silicon Nitride Photonic Platform2019In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 19, no 8, p. 5452-5458Article in journal (Refereed)
    Abstract [en]

    Single-photon sources and detectors are indispensable building blocks for integrated quantum photonics, a research field that is seeing ever increasing interest for numerous applications. In this work, we implemented essential components for a quantum key distribution transceiver on a single photonic chip. Plasmonic antennas on top of silicon nitride waveguides provide Purcell enhancement with a concurrent increase of the count rate, speeding up the microsecond radiative lifetime of IR-emitting colloidal PbS/CdS quantum dots (QDs). The use of low-fluorescence silicon nitride, with a waveguide loss smaller than 1 dB/cm, made it possible to implement high extinction ratio optical filters and low insertion loss spectrometers. Waveguide-coupled superconducting nanowire single-photon detectors allow for low time-jitter single-photon detection. To showcase the performance of the components, we demonstrate on-chip lifetime spectroscopy of PbS/CdS QDs. The method developed in this paper is predicted to scale down to single QDs, and newly developed emitters can be readily integrated on the chip-based platform.

  • 23.
    Fognini, A.
    et al.
    Delft Univ Technol, Kavli Inst Nanosci Delft, NL-2628 CJ Delft, Netherlands. hmadi, A..
    Ahmadi, A.
    Zeeshan, M.
    Fokkens, J. T.
    Gibson, S. J.
    Sherlekar, N.
    Daley, S. J.
    Dalacu, D.
    Poole, P. J.
    Jöns, Klaus D.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Reimer, M. E.
    Dephasing Free Photon Entanglement with a Quantum Dot2019In: ACS Photonics, E-ISSN 2330-4022, Vol. 6, no 7, p. 1656-1663Article in journal (Refereed)
    Abstract [en]

    Generation of photon pairs from quantum dots with near-unity entanglement fidelity has been a long-standing scientific challenge. It is generally thought that the nuclear spins limit the entanglement fidelity through spin flip dephasing processes. However, this assumption lacks experimental support. Here, we show two-photon entanglement with negligible dephasing from an indium rich single quantum dot comprising a nuclear spin of 9/2 when excited quasi-resonantly. This finding is based on a significantly close match between our entanglement measurements and our model that assumes no dephasing and takes into account the detection system's timing jitter and dark counts. We suggest that neglecting the detection system is responsible for the degradation of the measured entanglement fidelity in the past and not the nuclear spins. Therefore, the key to unity entanglement from quantum dots comprises a resonant excitation scheme and a detection system with ultralow timing jitter and dark counts.

  • 24.
    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.

  • 25.
    Gatti, Alessandra
    et al.
    CNR, Ist Foton & Nanotecnol, Piazza Leonardo Da Vinci 32, Milan, Italy.;Univ Insubria, Dipartimento Sci & Alta Tecnol, Via Valleggio 11, Como, Italy..
    Brambilla, Enrico
    Univ Insubria, Dipartimento Sci & Alta Tecnol, Via Valleggio 11, Como, Italy..
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Jedrkiewicz, Ottavia
    CNR, Ist Foton & Nanotecnol, Piazza Leonardo Da Vinci 32, Milan, Italy.;Univ Insubria, Dipartimento Sci & Alta Tecnol, Via Valleggio 11, Como, Italy..
    Golden ratio entanglement in hexagonally poled nonlinear crystals2018In: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 98, no 5, article id 053827Article in journal (Refereed)
    Abstract [en]

    This work analyzes the quantum state of twin photons and twin beams generated by parametric down-conversion in a hexagonally poled photonic crystal, characterized by the simultaneous presence of two nonlinear processes sustained by two vectors of the reciprocal lattice. In those special points of the fluorescence spectrum where the two processes coexist, we show that a tripartite entangled state is realized, equivalent to a single parametric process followed by a beam splitter. By proper angle tuning, a peculiar resonance condition is reached, with a transition to a four-mode entanglement, dominated by the golden ratio of the segment phi = (1 + root 5)/2. A maximal coherence between the two nonlinear processes is established here, as the overall process is shown to be equivalent to two independent parametric processes followed by a beam splitter. We offer an interpretation of the occurrence of the golden ratio in this system based on an analogy between the evolution of the light modes and the Fibonacci sequence.

  • 26.
    Gourgues, Ronan
    et al.
    Single Quantum BV, NL-2628 CH Delft, Netherlands..
    Los, Johannes W. N.
    Single Quantum BV, NL-2628 CH Delft, Netherlands..
    Zichi, Julien
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Chang, Jin
    Delft Univ Technol, Fac Appl Sci, ImPhys Dept, Opt Res Grp, Lorentzweg 1, NL-2628 CJ Delft, Netherlands..
    Kalhor, Nima
    Single Quantum BV, NL-2628 CH Delft, Netherlands..
    Bulgarini, Gabriele
    Single Quantum BV, NL-2628 CH Delft, Netherlands..
    Borenbos, Sander N.
    Single Quantum BV, NL-2628 CH Delft, Netherlands..
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Zadeh, Iman Esmaeil
    Delft Univ Technol, Fac Appl Sci, ImPhys Dept, Opt Res Grp, Lorentzweg 1, NL-2628 CJ Delft, Netherlands..
    Superconducting nanowire single photon detectors operating at temperature from 4 to 7 K2019In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 27, no 17, p. 24601-24609Article in journal (Refereed)
    Abstract [en]

    We experimentally investigate the performance of NbTiN superconducting nanowire single photon detectors above the base temperature of a conventional Gifford-McMahon cryocooler (2.5 K). By tailoring design and thickness (8-13 nm) of the detectors, high performance, high operating temperature, single-photon detection from the visible to telecom wavelengths are demonstrated. At 4.3 K, a detection efficiency of 82 % at 785 nm wavelength and a timing jitter of 30 +/- 0.3 ps are achieved. In addition, for 1550 nm and similar operating temperature we measured a detection efficiency as high as 64 %. Finally, we show that at temperatures up to 7 K, unity internal efficiency is maintained for the visible spectrum. Our work is particularly important to allow for the large scale implementation of superconducting single photon detectors in combination with heat sources such as free-space optical windows, cryogenic electronics, microwave sources and active optical components for complex quantum optical experiments and bio-imaging.

  • 27.
    Gourgues, Ronan
    et al.
    Single Quantum BV, NL-2628 CH Delft, Netherlands..
    Zadeh, Iman Esmaeil
    Single Quantum BV, NL-2628 CH Delft, Netherlands.;Delft Univ Technol, ImPhys Dept, Opt Res Grp, Fac Appl Sci, Lorentzweg 1, NL-2628 CJ Delft, Netherlands..
    Elshaari, Ali W.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Bulgarini, Gabriele
    Single Quantum BV, NL-2628 CH Delft, Netherlands..
    Los, Johannes W. N.
    Single Quantum BV, NL-2628 CH Delft, Netherlands..
    Zichi, Julien
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Dalacu, Dan
    Natl Res Council Canada, Ottawa, ON K1A 0R6, Canada..
    Poole, Philip J.
    Natl Res Council Canada, Ottawa, ON K1A 0R6, Canada..
    Dorenbos, Sander N.
    Single Quantum BV, NL-2628 CH Delft, Netherlands..
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Controlled integration of selected detectors and emitters in photonic integrated circuits2019In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 27, no 3, p. 3710-3716Article in journal (Refereed)
    Abstract [en]

    Integration of superconducting nanowire single-photon detectors and quantum sources with photonic waveguides is crucial for realizing advanced quantum integrated circuits. However, scalability is hindered by stringent requirements on high-performance detectors. Here we overcome the yield limitation by controlled coupling of photonic channels to pre-selected detectors based on measuring critical current, timing resolution, and detection efficiency. As a proof of concept of our approach, we demonstrate a hybrid on-chip full-transceiver consisting of a deterministically integrated detector coupled to a selected nanowire quantum dot through a filtering circuit made of a silicon nitride waveguide and a ring resonator filter, delivering 100 dB suppression of the excitation laser. In addition, we perform extensive testing of the detectors before and after integration in the photonic circuit and show that the high performance of the superconducting nanowire detectors, including timing jitter down to 23 +/- 3 ps, is maintained. Our approach is fully compatible with wafer-level automated testing in a cleanroom environment. 

  • 28.
    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.

  • 29. 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.

  • 30.
    Hills, M. J.
    et al.
    STFC Rutherford Appleton Lab, Harwell Campus, Didcot OX11 0QX, Oxon, England..
    Bradshaw, T. W.
    STFC Rutherford Appleton Lab, Harwell Campus, Didcot OX11 0QX, Oxon, England..
    Dobrovolskiy, S.
    Single Quantum BV, NL-2628 CH Delft, Netherlands..
    Dorenbos, S. N.
    Single Quantum BV, NL-2628 CH Delft, Netherlands..
    Gemmell, N. R.
    Univ Sussex, Dept Phys & Astron, Brighton BN1 9RH, E Sussex, England..
    Green, B.
    STFC Rutherford Appleton Lab, Harwell Campus, Didcot OX11 0QX, Oxon, England..
    Heath, R. M.
    Univ Glasgow, Sch Engn, Glasgow G12 8QQ, Lanark, Scotland..
    Rawlings, T.
    STFC Rutherford Appleton Lab, Harwell Campus, Didcot OX11 0QX, Oxon, England..
    Tsimvrakidis, K.
    Univ Glasgow, Sch Engn, Glasgow G12 8QQ, Lanark, Scotland..
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Crook, M. R.
    STFC Rutherford Appleton Lab, Harwell Campus, Didcot OX11 0QX, Oxon, England..
    Hadfield, R. H.
    Univ Glasgow, Sch Engn, Glasgow G12 8QQ, Lanark, Scotland..
    A compact 4 K cooling system for superconducting nanowire single photon detectors2019In: 27TH INTERNATIONAL CRYOGENICS ENGINEERING CONFERENCE AND INTERNATIONAL CRYOGENIC MATERIALS CONFERENCE 2018 (ICEC-ICMC 2018) / [ed] Bradshaw, T Kirichek, O Vandore, J, IOP PUBLISHING LTD , 2019, article id 012193Conference paper (Refereed)
    Abstract [en]

    Compact, low power, robust closed-cycle cooling platforms are a key requirement for emerging low temperature quantum technologies. We have repurposed a 4 K Stirling/Joule-Thomson cooler built for the Planck space mission into a flexible demonstration system. We have verified a cooling power of 4mW at 4.7K. We have installed a fibre-coupled superconducting nanowire single-photon detector in this platform and deployed it for two key advanced infrared photon counting applications: single-photon LIDAR and dosimetry for laser cancer treatment. We discuss proposed improvements to the Stirling cooler design for increased cooling power, manufacturability and turn-key operation.

  • 31. Hu, Xiaolong
    et al.
    Hu, Nan
    Meng, Yun
    Zou, Kai
    Xu, Liang
    Lan, Xiaojian
    Chi, Xiaoming
    Gu, Chao
    Cheng, Yuhao
    Wu, Hao
    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.
    Superconducting nanowire single-photon detectors at the infrared spectrum range: detection efficiency and timing jitter2019In: TERAHERTZ, RF, MILLIMETER, AND SUBMILLIMETER-WAVE TECHNOLOGY AND APPLICATIONS XII / [ed] Sadwick, LP Yang, T, 2019Conference paper (Refereed)
    Abstract [en]

    This paper reviews some recent research progress in superconducting nanowire single-photon detectors (SNSPDs) at the infrared spectrum range, with particular emphasis on detection efficiency and timing jitter. For detection efficiency, we present fractal SNSPDs with reduced polarization sensitivity; for timing jitter, we present two mechanisms of device timing jitter - vortex-crossing-induced timing jitter and spatial-inhomogeneity-induced timing jitter.

  • 32.
    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)
  • 33. Kilinc, D
    et al.
    Blasiak, A
    Baghban, Mohammad Amin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Carville, N. C.
    Al-Adli, A.
    Al-Shammari, R. M.
    Rice, J. H.
    Lee, G. U.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Rodriguez, B. J.
    Charge and topography patterned lithium niobate provides physical cues to fluidically isolated cortical axons2017In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 110, no 5, article id 053702Article in journal (Refereed)
    Abstract [en]

    In vitro devices that combine chemotactic and physical cues are needed for understanding how cells integrate different stimuli. We explored the suitability of lithium niobate (LiNbO3), a transparent ferroelectric material that can be patterned with electrical charge domains and micro/ nanotopography, as a neural substrate. On flat LiNbO3 z-surfaces with periodically alternating charge domains, cortical axons are partially aligned with domain boundaries. On submicron-deep etched trenches, neurites are aligned with the edges of the topographical features. Finally, we bonded a bicompartmental microfluidic chip to LiNbO3 surfaces patterned by etching, to create isolated axon microenvironments with predefined topographical cues. LiNbO3 is shown to be an emerging neuron culture substrate with tunable electrical and topographical properties that can be integrated with microfluidic devices, suitable for studying axon growth and guidance mechanisms under combined topographical/chemical stimuli.

  • 34.
    Koeck, A.
    et al.
    Mat Ctr Leoben Forsch GmbH, A-8700 Leoben, Austria..
    Deluca, M.
    Mat Ctr Leoben Forsch GmbH, A-8700 Leoben, Austria..
    Sosada-Ludwikowska, F.
    Mat Ctr Leoben Forsch GmbH, A-8700 Leoben, Austria..
    Wimmer-Teubenbacher, R.
    Mat Ctr Leoben Forsch GmbH, A-8700 Leoben, Austria..
    Lackner, E.
    Ams AG, A-8140 Premstatten, Austria..
    Rohracher, K.
    Ams AG, A-8140 Premstatten, Austria..
    Wachmann, E.
    Ams AG, A-8140 Premstatten, Austria..
    Niehaus, J. S.
    Fraunhofer Inst Appl Polymer Res, IAP CAN, D-14476 Potsdam, Germany..
    Becker, S.
    Fraunhofer Inst Appl Polymer Res, IAP CAN, D-14476 Potsdam, Germany..
    Tokmak, Oe.
    Fraunhofer Inst Appl Polymer Res, IAP CAN, D-14476 Potsdam, Germany..
    Steinhauer, Stephan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Sowwan, M.
    Okinawa Inst Sci & Technol, Grad Univ, Okinawa, Japan..
    Singh, V.
    Okinawa Inst Sci & Technol, Grad Univ, Okinawa, Japan..
    Multifunctional Nanoparticles - Key for Optimizing Chemical Nanosensors2018In: ASDAM 2018 - Proceedings: 12th International Conference on Advanced Semiconductor Devices and Microsystems / [ed] Breza, J Donoval, D Vavrinsky, E, IEEE, 2018, p. 227-231, article id 8544608Conference paper (Refereed)
    Abstract [en]

    Multifunctional nanoparticles are key for optimizing the performance of chemical sensor devices. We have fabricated a variety of nanosensor devices based on ultrathin metal oxide films and nanowires, which have been integrated on CMOS-based micro-hotplate chips. These sensors have been functionalized with metallic as well as bimetallic nanoparticles. We have demonstrated that Pt-NPs or NiPt-NPs, strongly increase the sensitivity to carbon monoxide and supress the cross selectivity to humidity in case of SnO2 thin film based devices. We have employed both nanoparticles synthesized in solution, which are ink-jet deposited, as well as nanoparticles, which are implemented by gas phase synthesis directly on the micro-hotplate chips. The Pt-functionalized SnO2-thin film sensors show a strongly increased response to CO, which is almost independent of humidity as compared to the bare SnO2-thin film sensor. The highest response of more than 90% has been achieved with NiPt-functionalized SnO2-thin film sensors at a very low operation temperature of only 150 degrees C.

  • 35.
    Krmpot, Aleksandar J.
    et al.
    Karolinska Inst, CMM, Dept Clin Neurosci CNS, S-17176 Stockholm, Sweden.;Univ Belgrade, Inst Phys Belgrade, Belgrade 11080, Serbia..
    Nikolic, Stanko N.
    Karolinska Inst, CMM, Dept Clin Neurosci CNS, S-17176 Stockholm, Sweden.;Univ Belgrade, Inst Phys Belgrade, Belgrade 11080, Serbia..
    Oasa, Sho
    Karolinska Inst, CMM, Dept Clin Neurosci CNS, S-17176 Stockholm, Sweden..
    Papadopoulos, Dimitrios K.
    Max Planck Inst Mol Cell Biol & Genet, D-01307 Dresden, Germany.;Univ Edinburgh, Inst Genet & Mol Med, MRC Human Genet Unit, Edinburgh EH4 2XU, Midlothian, Scotland..
    Vitali, Marco
    Sicoya GmbH, D-12489 Berlin, Germany..
    Oura, Makoto
    Hokkaido Univ, Fac Adv Life Sci, Lab Mol Cell Dynam, Sapporo, Hokkaido 0010021, Japan..
    Mikuni, Shintaro
    Hokkaido Univ, Fac Adv Life Sci, Lab Mol Cell Dynam, Sapporo, Hokkaido 0010021, Japan..
    Thyberg, Per
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Tisa, Simone
    MPD, I-39100 Bolzano, Italy..
    Kinjo, Masataka
    Hokkaido Univ, Fac Adv Life Sci, Lab Mol Cell Dynam, Sapporo, Hokkaido 0010021, Japan..
    Nilsson, Lennart
    Karolinska Inst, Dept Biosci & Nutr, S-14183 Huddinge, Sweden..
    Terenius, Lars
    Karolinska Inst, CMM, Dept Clin Neurosci CNS, S-17176 Stockholm, Sweden..
    Rigler, Rudolf
    Karolinska Inst, CMM, Dept Clin Neurosci CNS, S-17176 Stockholm, Sweden.;Karolinska Inst, Dept Med Biochem & Biophys MBB, S-17177 Stockholm, Sweden..
    Vukojevic, Vladana
    Karolinska Inst, CMM, Dept Clin Neurosci CNS, S-17176 Stockholm, Sweden..
    Functional Fluorescence Microscopy Imaging: Quantitative Scanning-Free Confocal Fluorescence Microscopy for the Characterization of Fast Dynamic Processes in Live Cells2019In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 91, no 17, p. 11129-11137Article in journal (Refereed)
    Abstract [en]

    Functional fluorescence microscopy imaging (fFMI), a time-resolved (21 mu s/frame) confocal fluorescence microscopy imaging technique without scanning, is developed for quantitative characterization of fast reaction-transport processes in solution and in live cells. The method is based on massively parallel fluorescence correlation spectroscopy (FCS). Simultaneous excitation of fluorescent molecules in multiple spots in the focal plane is achieved using a diffractive optical element (DOE). Fluorescence from the DOE-generated 1024 illuminated spots is detected in a confocal arrangement by a matching matrix detector comprising 32 x 32 single-photon avalanche photodiodes (SPADs). Software for data acquisition and fast auto- and cross-correlation analysis by parallel signal processing using a graphic processing unit (GPU) allows temporal autocorrelation across all pixels in the image frame in 4 s and cross-correlation between first- and second-order neighbor pixels in 45 s. We present here this quantitative, time-resolved imaging method with single-molecule sensitivity and demonstrate its usefulness for mapping in live cell location-specific differences in the concentration and translational diffusion of molecules in different subcellular compartments. In particular, we show that molecules without a specific biological function, e.g., the enhanced green fluorescent protein (eGFP), exhibit uniform diffusion. In contrast, molecules that perform specialized biological functions and bind specifically to their molecular targets show location-specific differences in their concentration and diffusion, exemplified here for two transcription factor molecules, the glucocorticoid receptor (GR) before and after nuclear translocation and the Sex combs reduced (Scr) transcription factor in the salivary gland of Drosophila ex vivo.

  • 36.
    Machhadani, Houssaine
    et al.
    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.
    Bougerol, Catherine
    Univ Grenoble Alpes, CNRS Inst Neel, 25 Av Martyrs, F-38000 Grenoble, France..
    Lequien, Stephane
    Univ Grenoble Alpes, CEA INAC MEM, 17 Av Martyrs, F-38000 Grenoble, France..
    Thomassin, Jean-Luc
    Univ Grenoble Alpes, CEA INAC PHELIQS, 17 Av Martyrs, F-38000 Grenoble, France..
    Mollard, Nicolas
    Univ Grenoble Alpes, CEA INAC MEM, 17 Av Martyrs, F-38000 Grenoble, France..
    Mukhtarova, Anna
    Univ Grenoble Alpes, CEA INAC PHELIQS, 17 Av Martyrs, F-38000 Grenoble, France..
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gerard, Jean-Michel
    Univ Grenoble Alpes, CEA INAC PHELIQS, 17 Av Martyrs, F-38000 Grenoble, France..
    Monroy, Eva
    Univ Grenoble Alpes, CEA INAC PHELIQS, 17 Av Martyrs, F-38000 Grenoble, France..
    Improvement of the critical temperature of NbTiN films on III-nitride substrates2019In: Superconductors Science and Technology, ISSN 0953-2048, E-ISSN 1361-6668, Vol. 32, no 3, article id 035008Article in journal (Refereed)
    Abstract [en]

    In this paper, we study the impact of using III-nitride semiconductors (GaN, AlN) as substrates for ultrathin (11 nm) superconducting films of NbTiN deposited by reactive magnetron sputtering. The resulting NbTiN layers are (111)-oriented, fully relaxed, and they keep an epitaxial relation with the substrate. The higher critical superconducting temperature (T-c = 11.8 K) was obtained on AIN-on-sapphire, which was the substrate with smaller lattice mismatch with NbTiN. We attribute this improvement to a reduction of the NbTiN roughness, which appears associated with the relaxation of the lattice misfit with the substrate. On AlN-on-sapphire, superconducting nanowire single photon detectors were fabricated and tested, obtaining external quantum efficiencies that are in excellent agreement with theoretical calculations.

  • 37. Machhadani, Houssaine
    et al.
    Zichi, Julien
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Bougerol, Catherine
    Lequien, Stéphane
    Thomassin, Jean-Luc
    Mollard, Nicolas
    Mukhtarova, Anna
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Gérard, Jean-Michel
    Monroy, Eva
    Improvement of the critical temeprature of NbTiN films on III-nitride substrates2019In: Superconductors Science and Technology, ISSN 0953-2048, E-ISSN 1361-6668, Vol. 32, no 035008Article in journal (Refereed)
    Abstract [en]

    In this paper, we study the impact of using III-nitride semiconductors (GaN, AlN) as substrates for ultrathin (11 nm) superconducting films of NbTiN deposited by reactive magnetron sputtering. The resulting NbTiN layers are (111)-oriented, fully relaxed, and they keep an epitaxial relation with the substrate. The higher critical superconducting temperature (T c = 11.8 K) was obtained on AlN-on-sapphire, which was the substrate with smaller lattice mismatch with NbTiN. We attribute this improvement to a reduction of the NbTiN roughness, which appears associated with the relaxation of the lattice misfit with the substrate. On AlN-on-sapphire, superconducting nanowire single photon detectors were fabricated and tested, obtaining external quantum efficiencies that are in excellent agreement with theoretical calculations.

  • 38.
    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.

  • 39. Mukhtarova, Anna
    et al.
    Redaelli, Luca
    Hazra, Dibyendu
    Machhadani, Houssaine
    Lequien, Stéphane
    Hofheinz, Max
    Thomassin, Jean-Luc
    Gustavo, Frederic
    Zichi, Julien
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Monroy, Eva
    Gérard, Jean-Michel
    Polarization-insensitive fiber-coupled superconducting-nanowire single photon detector using high-index dielectric capping layer2018In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 26, no 13Article 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 μm, in excellent agreement with simulations.

  • 40. 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.

  • 41.
    Ojemyr, Linda Nasvik
    et al.
    Stockholm Univ, Dept Biochem & Biophys, Arrhenius Labs Nat Sci, S-10691 Stockholm, Sweden..
    Sanden, Tor
    Royal Inst Technol, Dept Appl Phys, Stockholm, Sweden..
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Brzezinski, Peter
    Stockholm Univ, Dept Biochem & Biophys, Arrhenius Labs Nat Sci, S-10691 Stockholm, Sweden..
    Membrane-facilitated proton transfer to the surface of a membrane-spanning proton transporter2010In: Biochimica et Biophysica Acta - Bioenergetics, ISSN 0005-2728, E-ISSN 1879-2650, Vol. 1797, p. 98-98Article in journal (Other academic)
  • 42.
    Ojemyr, Linda
    et al.
    Stockholm Univ, Arrhenius Labs Nat Sci, Dept Biochem & Biophys, Stockholm, Sweden..
    Sanden, Tor
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Brzezinski, Peter
    Stockholm Univ, Arrhenius Labs Nat Sci, Dept Biochem & Biophys, Stockholm, Sweden..
    Proton transfer along surfaces of membranes and membrane-proteins2008In: Biochimica et Biophysica Acta - Bioenergetics, ISSN 0005-2728, E-ISSN 1879-2650, Vol. 1777, p. S94-S94Article in journal (Other academic)
  • 43.
    Ottonello-Briano, Floria
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Errando-Herranz, Carlos
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems. KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Gylfason, Kristinn
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    On-chip dispersion spectroscopy of mid-infrared molecular fingerprints using a microring resonatorManuscript (preprint) (Other academic)
  • 44.
    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.

  • 45. Peng, Xingyun
    et al.
    Huang, Bingru
    Pu, Rui
    Liu, Haichun
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Zhang, Tao
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Zhan, Qiuqiang
    Ågren, Hans
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Fast upconversion super-resolution microscopy with 10 μs per pixel dwell times2019In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, no 4, p. 1563-1569Article in journal (Refereed)
  • 46. Quack, Niels
    et al.
    Sattari, Hamed
    Takabayashi, Alain Yuji
    Zhang, Yu
    Edinger, Pierre
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Errando-Herranz, Carlos
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Gylfason, Kristinn
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Wang, Xiaojing
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Niklaus, Frank
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Jezzini, Moises
    Hwang, H. Y.
    O'Brien, Peter
    Porcel, Marco
    Arce, Cristina
    Kumar, Saurav
    Abasahl, Banafsheh
    Verheyen, Peter
    Bogaerts, Wim
    Exploiting Mechanics at the Nanoscale to Enhance Photonic Integrated Circuits2019In: 2019 Optical Fiber Communications Conference and Exhibition, OFC 2019 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2019, p. 1-3, article id 8696652Conference paper (Refereed)
    Abstract [en]

    With the maturing and the increasing complexity of Silicon Photonics technology, novel avenues are pursued to reduce power consumption and to provide enhanced functionality: exploiting mechanical movement in advanced Silicon Photonic Integrated Circuits provides a promising path to access a strong modulation of the effective index and to low power consumption by employing mechanically stable and thus non-volatile states. In this paper, we will discuss recent achievements in the development of MEMS enabled systems in Silicon Photonics and outline the roadmap towards reconfigurable general Photonic Integrated Circuits.

  • 47. Quack, Niels
    et al.
    Sattari, Hamed
    Takabayashi, Alain Yuji
    Zhang, Yu
    Errando-Herranz, Carlos
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Edinger, Pierre
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Gylfason, Kristinn
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Exploiting Mechanics at the Micro- and Nanoscale for Efficient Reconfiguration of Photonic Integrated Circuits2019In: IEEE Photonics Society Summer Topical Meeting Series 2019, SUM 2019, 2019, p. 1-1, article id 8795036Conference paper (Refereed)
    Abstract [en]

    We exploit Micro- & Nano-Electro-Mechanical Systems in Photonic Integrated Circuits to perform basic photonic operations, including phase shifting, attenuation and switching. Due to their small footprint and low insertion loss, Photonic MEMS are highly scalable, while mechanical latching mechanisms can offer zero steady state power consumption.

  • 48.
    Reindl, Marcus
    et al.
    Johannes Kepler Univ Linz, Inst Semicond & Solid State Phys, A-4040 Linz, Austria..
    Huber, Daniel
    Johannes Kepler Univ Linz, Inst Semicond & Solid State Phys, A-4040 Linz, Austria..
    Schimpf, Christian
    Johannes Kepler Univ Linz, Inst Semicond & Solid State Phys, A-4040 Linz, Austria..
    da Silva, Saimon F. Covre
    Johannes Kepler Univ Linz, Inst Semicond & Solid State Phys, A-4040 Linz, Austria..
    Rota, Michele B.
    Johannes Kepler Univ Linz, Inst Semicond & Solid State Phys, A-4040 Linz, Austria.;Sapienza Univ Rome, Dept Phys, I-00185 Rome, Italy..
    Huang, Huiying
    Johannes Kepler Univ Linz, Inst Semicond & Solid State Phys, A-4040 Linz, Austria..
    Zwiller, Val
    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.
    Rastelli, Armando
    Johannes Kepler Univ Linz, Inst Semicond & Solid State Phys, A-4040 Linz, Austria.;Johannes Kepler Univ Linz, Linz Inst Technol, A-4040 Linz, Austria..
    Trotta, Rinaldo
    Johannes Kepler Univ Linz, Inst Semicond & Solid State Phys, A-4040 Linz, Austria.;Sapienza Univ Rome, Dept Phys, I-00185 Rome, Italy..
    All-photonic quantum teleportation using on-demand solid-state quantum emitters2018In: Science Advances, E-ISSN 2375-2548, Vol. 4, no 12, article id eaau1255Article in journal (Refereed)
    Abstract [en]

    All-optical quantum teleportation lies at the heart of quantum communication science and technology. This quantum phenomenon is built up around the nonlocal properties of entangled states of light that, in the perspective of real-life applications, should be encoded on photon pairs generated on demand. Despite recent advances, however, the exploitation of deterministic quantum light sources in push-button quantum teleportation schemes remains a major open challenge. Here, we perform an important step toward this goal and show that photon pairs generated on demand by a GaAs quantum dot can be used to implement a teleportation protocol whose fidelity violates the classical limit (by more than 5 SDs) for arbitrary input states. Moreover, we develop a theoretical framework that matches the experimental observations and that defines the degree of entanglement and indistinguishability needed to overcome the classical limit independently of the input state. Our results emphasize that on-demand solid-state quantum emitters are one of the most promising candidates to realize deterministic quantum teleportation in practical quantum networks.

  • 49.
    Ribet, Federico
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    De Luca, Eleonora
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Ottonello Briano, Floria
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Swillo, Marcin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Roxhed, Niclas
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Stemme, Göran
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Zero-insertion-loss optical shutter based on electrowetting-on-dielectric actuation of opaque ionic liquid microdroplets2019In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 115, no 7, article id 073502Article in journal (Refereed)
    Abstract [en]

    This article reports a broad-band optical shutter based on microdroplet actuation with zero optical insertion loss in the open state. These features are achieved by electrowetting-on-dielectric (EWOD) actuation of opaque ionic liquid microdroplets. The negligible vapor pressure of ionic liquids allows the device to robustly operate in open air, unlike previously proposed EWOD-based systems in which the light crosses several attenuating and reflective layers, preventing broad-band operation and creating insertion losses > 14%. The presented device provides an attenuation of 78dB in the closed state and a transmission of >99.99999% in the open state and can operate in the visible and mid-infrared wavelength range. Moreover, the switch can sustain larger incoming laser powers (5 mW continuous exposure or up to 3h of continuous exposure at similar to 100mW) compared to the values reported for other state-of-the-art EWOD-based shutters. Additionally, the proposed device is compact, operates with low voltage (<25V peak voltage), and features zero static power consumption.

  • 50.
    Schaper, Klaus
    et al.
    Univ Dusseldorf, Dept Chem, D-40225 Dusseldorf, Germany..
    Bier, Brigitte
    Univ Dusseldorf, Dept Chem, D-40225 Dusseldorf, Germany..
    Taureg, Patrick
    Univ Dusseldorf, Dept Chem, D-40225 Dusseldorf, Germany..
    von Dahlen, Steffen
    Pfiffi, Daniela
    Seidel, Claus A. M.
    Chmyrov, Andriy
    KTH.
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    PHYS 624-Strategies to improve signal strength and photostability of fluorophors in single molecule spectroscopy2007In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 234Article in journal (Other academic)
12 1 - 50 of 69
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