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ACS Photonics

Weichun Zhang, Martín Caldarola, Xuxing Lu, Michel Orrit
Plasmonic enhancement of two-photon-excited fluorescence is not only of fundamental interest but also appealing for many bioimaging and photonic applications. The high peak intensity required for two-photon excitation may cause shape changes in plasmonic nanostructures, as well as transient plasmon broadening. Yet, in this work, we report on strong enhancement of the two-photon-excited photoluminescence of single colloidal quantum dots close to isolated chemically synthesized gold nanorods. Upon resonant excitation of the localized surface plasmon resonance, a gold nanorod can enhance the photoluminescence of a single quantum dot more than 10 000-fold...
July 18, 2018: ACS Photonics
Omri Bar-Elli, Dan Steinitz, Gaoling Yang, Ron Tenne, Anastasia Ludwig, Yung Kuo, Antoine Triller, Shimon Weiss, Dan Oron
Properly designed colloidal semiconductor quantum dots (QDs) have already been shown to exhibit high sensitivity to external electric fields via the quantum confined Stark effect (QCSE). Yet, detection of the characteristic spectral shifts associated with the effect of the QCSE has traditionally been painstakingly slow, dramatically limiting the sensitivity of these QD sensors to fast transients. We experimentally demonstrate a new detection scheme designed to achieve shot-noise-limited sensitivity to emission wavelength shifts in QDs, showing feasibility for their use as local electric field sensors on the millisecond time scale...
July 18, 2018: ACS Photonics
Bart van Dam, Clara I Osorio, Mark A Hink, Remmert Muller, A Femius Koenderink, Katerina Dohnalova
Light-emitting silicon nanoparticles (Si-NPs) are interesting for lighting applications due to their nontoxicity, chemical robustness, and photostability; however, they are not practically considered due to their low emission efficiencies. While large Si-NPs emitting in the red to infrared spectral region show ensemble emission quantum efficiencies up to 60%, the emission efficiencies of smaller Si-NPs, emitting in the visible spectral range, are far lower, typically below 10-20%. In this work, we test this efficiency limit by measuring for the first time the internal quantum efficiency (IQE), i...
June 20, 2018: ACS Photonics
Charles Möhl, Arko Graf, Felix J Berger, Jan Lüttgens, Yuriy Zakharko, Victoria Lumsargis, Malte C Gather, Jana Zaumseil
We demonstrate the formation and tuning of charged trion-polaritons in polymer-sorted (6,5) single-walled carbon nanotubes in a planar metal-clad microcavity at room temperature. The positively charged trion-polaritons were induced by electrochemical doping and characterized by angle-resolved reflectance and photoluminescence spectroscopy. The doping level of the nanotubes within the microcavity was controlled by the applied bias and thus enabled tuning from mainly excitonic to a mixture of exciton and trion transitions...
June 20, 2018: ACS Photonics
Kirill Grishunin, Thomas Huisman, Guanqiao Li, Elena Mishina, Theo Rasing, Alexey V Kimel, Kailing Zhang, Zuanming Jin, Shixun Cao, Wei Ren, Guo-Hong Ma, Rostislav V Mikhaylovskiy
Magnon-polaritons are shown to play a dominant role in the propagation of terahertz (THz) waves through TmFeO3 orthoferrite, if the frequencies of the waves are in the vicinity of the quasi-antiferromagnetic spin resonance mode. Both time-domain THz transmission and emission spectroscopies reveal clear beatings between two modes with frequencies slightly above and slightly below this resonance, respectively. Rigorous modeling of the interaction between the spins of TmFeO3 and the THz light shows that the frequencies correspond to the upper and lower magnon-polariton branches...
April 18, 2018: ACS Photonics
Franz-Philipp Schmidt, Arthur Losquin, Ferdinand Hofer, Andreas Hohenau, Joachim R Krenn, Mathieu Kociak
Due to a vanishing dipole moment, radial breathing modes in small flat plasmonic nanoparticles do not couple to light and have to be probed with a near-field source, as in electron energy loss spectroscopy (EELS). With increasing particle size, retardation gives rise to light coupling, enabling probing breathing modes optically or by cathodoluminescence (CL). Here, we investigate single silver nanodisks with diameters of 150-500 nm by EELS and CL in an electron microscope and quantify the EELS/CL ratio, which corresponds to the ratio of full to radiative damping of the breathing mode...
March 21, 2018: ACS Photonics
Odysseas Tsilipakos, Thomas Koschny, Costas M Soukoulis
Metasurfaces impart phase discontinuities on impinging electromagnetic waves that are typically limited to 0-2π. Here, we demonstrate that multiresonant metasurfaces can break free from this limitation and supply arbitrarily large, tunable time delays over ultrawide bandwidths. As such, ultrathin metasurfaces can act as the equivalent of thick bulk structures by emulating the multiple geometric resonances of three-dimensional systems that originate from phase accumulation with effective material resonances implemented on the surface itself via suitable subwavelength meta-atoms...
March 21, 2018: ACS Photonics
Johannes Flick, Christian Schäfer, Michael Ruggenthaler, Heiko Appel, Angel Rubio
We introduce a simple scheme to efficiently compute photon exchange-correlation contributions due to the coupling to transversal photons as formulated in the newly developed quantum-electrodynamical density-functional theory (QEDFT).1-5 Our construction employs the optimized-effective potential (OEP) approach by means of the Sternheimer equation to avoid the explicit calculation of unoccupied states. We demonstrate the efficiency of the scheme by applying it to an exactly solvable GaAs quantum ring model system, a single azulene molecule, and chains of sodium dimers, all located in optical cavities and described in full real space...
March 21, 2018: ACS Photonics
Jongmin Park, Hyungsoon Im, Seonki Hong, Cesar M Castro, Ralph Weissleder, Hakho Lee
Extracellular vesicles (EVs), including exosomes, are nanoscale membrane particles shed from cells and contain cellular proteins whose makeup could inform cancer diagnosis and treatment. Most analyses have focused on surface proteins while analysis of intravesicular proteins has been more challenging. Herein, we report an EV screening assay for both intravesicular and transmembrane proteins using a nanoplasmonic sensor. Termed iNPS (intravesicular nanoplasmonic system), this platform used nanohole-based surface plasmon resonance (SPR) for molecular detection...
February 21, 2018: ACS Photonics
Anna C Tasolamprou, Thomas Koschny, Maria Kafesaki, Costas M Soukoulis
We present the design of a dielectric inverse photonic crystal structure that couples line-defect waveguide propagating modes into highly directional beams of controllable directionality. The structure utilizes a triangular lattice made of air holes drilled in an infinitely thick Si slab, and it is designed for operation in the near-infrared and optical regime. The structure operation is based on the excitation and manipulation of dark dielectric surface states, in particular on the tailoring of the dark states' coupling to outgoing radiation...
November 15, 2017: ACS Photonics
Andrea Crespi, Marco Bentivegna, Ioannis Pitsios, Davide Rusca, Davide Poderini, Gonzalo Carvacho, Vincenzo D'Ambrosio, Adán Cabello, Fabio Sciarrino, Roberto Osellame
In classical physics, properties of objects exist independently of the context, i.e., whether and how measurements are performed. Quantum physics showed this assumption to be wrong, and that Nature is indeed "contextual". Contextuality has been observed in the simplest physical systems, such as single particles, and plays fundamental roles in quantum computation advantage. Here, we demonstrate for the first time quantum contextuality in an integrated photonic chip. The chip implements different combinations of measurements on a single photon delocalized on four distinct spatial modes, showing violations of a Clauser-Horne-Shimony-Holt (CHSH)-like noncontextuality inequality...
November 15, 2017: ACS Photonics
Antonio Capretti, Arnon Lesage, Tom Gregorkiewicz
Nanoscale dielectric resonators and quantum-confined semiconductors have enabled unprecedented control over light absorption and excited charges, respectively. In this work, we embed luminescent silicon nanocrystals (Si-NCs) into a 2D array of SiO2 nanocylinders and experimentally prove a powerful concept: the resulting metamaterial preserves the radiative properties of the Si-NCs and inherits the spectrally selective absorption properties of the nanocylinders. This hierarchical approach provides increased photoluminescence (PL) intensity obtained without utilizing any lossy plasmonic components...
September 20, 2017: ACS Photonics
Rune Frederiksen, Gozde Tutuncuoglu, Federico Matteini, Karen L Martinez, Anna Fontcuberta I Morral, Esther Alarcon-Llado
Semiconductor nanowires are promising building blocks for next-generation photonics. Indirect proofs of large absorption cross sections have been reported in nanostructures with subwavelength diameters, an effect that is even more prominent in vertically standing nanowires. In this work we provide a three-dimensional map of the light around vertical GaAs nanowires standing on a substrate by using fluorescence confocal microscopy, where the strong long-range disruption of the light path along the nanowire is illustrated...
September 20, 2017: ACS Photonics
Dolfine Kosters, Anouk de Hoogh, Hans Zeijlemaker, Hakkı Acar, Nir Rotenberg, L Kuipers
We introduce core-shell plasmonic nanohelices, highly tunable structures that have a different response in the visible for circularly polarized light of opposite handedness. The glass core of the helices is fabricated using electron beam induced deposition and the pure gold shell is subsequently sputter coated. Optical measurements allow us to explore the chiral nature of the nanohelices, where differences in the response to circularly polarized light of opposite handedness result in a dissymmetry factor of 0...
July 19, 2017: ACS Photonics
Tao Ding, Rohit Chikkaraddy, Jan Mertens, Jeremy J Baumberg
Under UV illumination, polymer films can undergo chain scission and contract. Using this effect, tightly focused laser light is shown to develop runaway near-field concentration that drills sub-100 nm pits through a thin film. This subwavelength photolithography can be controlled in real time by monitoring laser scatter from the evolving holes, allowing systematic control of the void diameter. Our model shows how interference between the substrate and film together with near-field focusing by the evolving crevice directs this formation and predicts minimum pit sizes in films of 100 nm thickness on gold substrates...
June 21, 2017: ACS Photonics
Sarah Riazimehr, Satender Kataria, Rainer Bornemann, Peter Haring Bolívar, Francisco Javier Garcia Ruiz, Olof Engström, Andres Godoy, Max C Lemme
Graphene/silicon (G/Si) heterojunction based devices have been demonstrated as high responsivity photodetectors that are potentially compatible with semiconductor technology. Such G/Si Schottky junction diodes are typically in parallel with gated G/silicon dioxide (SiO2)/Si areas, where the graphene is contacted. Here, we utilize scanning photocurrent measurements to investigate the spatial distribution and explain the physical origin of photocurrent generation in these devices. We observe distinctly higher photocurrents underneath the isolating region of graphene on SiO2 adjacent to the Schottky junction of G/Si...
June 21, 2017: ACS Photonics
Tao Ding, Jan Mertens, Anna Lombardi, Oren A Scherman, Jeremy J Baumberg
The precise morphology of nanoscale gaps between noble-metal nanostructures controls their resonant wavelengths. Here we show photocatalytic plasmon-induced polymerization can locally enlarge the gap size and tune the plasmon resonances. We demonstrate light-directed programmable tuning of plasmons can be self-limiting. Selective control of polymer growth around individual plasmonic nanoparticles is achieved, with simultaneous real-time monitoring of the polymerization process in situ using dark-field spectroscopy...
June 21, 2017: ACS Photonics
Sarah Fischbach, Alexander Schlehahn, Alexander Thoma, Nicole Srocka, Timo Gissibl, Simon Ristok, Simon Thiele, Arsenty Kaganskiy, André Strittmatter, Tobias Heindel, Sven Rodt, Alois Herkommer, Harald Giessen, Stephan Reitzenstein
Integrated single-photon sources with high photon-extraction efficiency are key building blocks for applications in the field of quantum communications. We report on a bright single-photon source realized by on-chip integration of a deterministic quantum dot microlens with a 3D-printed multilens micro-objective. The device concept benefits from a sophisticated combination of in situ 3D electron-beam lithography to realize the quantum dot microlens and 3D femtosecond direct laser writing for creation of the micro-objective...
June 21, 2017: ACS Photonics
Marco Valenti, Anirudh Venugopal, Daniel Tordera, Magnus P Jonsson, George Biskos, Andreas Schmidt-Ott, Wilson A Smith
The conversion of light to electrical and chemical energy has the potential to provide meaningful advances to many aspects of daily life, including the production of energy, water purification, and optical sensing. Recently, plasmonic nanoparticles (PNPs) have been increasingly used in artificial photosynthesis (e.g., water splitting) devices in order to extend the visible light utilization of semiconductors to light energies below their band gap. These nanoparticles absorb light and produce hot electrons and holes that can drive artificial photosynthesis reactions...
May 17, 2017: ACS Photonics
Benedikt Schwarz, Christine A Wang, Leo Missaggia, Tobias S Mansuripur, Paul Chevalier, Michael K Connors, Daniel McNulty, Jeffrey Cederberg, Gottfried Strasser, Federico Capasso
Bifunctional active regions, capable of light generation and detection at the same wavelength, allow a straightforward realization of the integrated mid-infrared photonics for sensing applications. Here, we present a high performance bifunctional device for 8 μm capable of 1 W single facet continuous wave emission at 15 °C. Apart from the general performance benefits, this enables sensing techniques which rely on continuous wave operation, for example, heterodyne detection, to be realized within a monolithic platform and demonstrates that bifunctional operation can be realized at longer wavelength, where wavelength matching becomes increasingly difficult and that the price to be paid in terms of performance is negligible...
May 17, 2017: ACS Photonics
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