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ACS Photonics

Gernot Schaffernak, Markus K Krug, Martin Belitsch, Marija Gašparić, Harald Ditlbacher, Ulrich Hohenester, Joachim R Krenn, Andreas Hohenau
We show that the plasmon modes of vertically stacked Ag-SiO2 -Ag nanodisks can be understood and classified as hybridized surface and edge modes. We describe their universal dispersion relations and demonstrate that coupling-induced spectral shifts are significantly stronger for surface modes than for edge modes. The experimental data correspond well to numerical simulations. In addition, we estimate optical intensity enhancements of the stacked nanodisks in the range of 1000.
December 19, 2018: ACS Photonics
Aurelian John-Herpin, Andreas Tittl, Hatice Altug
Infrared spectroscopy is widely used for biomolecular studies, but struggles when investigating minute quantities of analytes due to the mismatch between vibrational cross sections and IR wavelengths. It is therefore beneficial to enhance absorption signals by confining the infrared light to deeply subwavelength volumes comparable in size to the biomolecules of interest. This can be achieved with surface-enhanced infrared absorption spectroscopy, for which plasmonic nanorod antennas represent the predominant implementation...
October 17, 2018: ACS Photonics
Emre Yüce, Jin Lian, Sergei Sokolov, Jacopo Bertolotti, Sylvain Combrié, Gaëlle Lehoucq, Alfredo De Rossi, Allard P Mosk
Resonant cavities with high quality factor and small mode volume provide crucial enhancement of light-matter interactions in nanophotonic devices that transport and process classical and quantum information. The production of functional circuits containing many such cavities remains a major challenge, as inevitable imperfections in the fabrication detune the cavities, which strongly affects functionality such as transmission. In photonic crystal waveguides, intrinsic disorder gives rise to high- Q localized resonances through Anderson localization; however their location and resonance frequencies are completely random, which hampers functionality...
October 17, 2018: ACS Photonics
Eric A Muller, Benjamin Pollard, Hans A Bechtel, Ronen Adato, Dordaneh Etezadi, Hatice Altug, Markus B Raschke
Optical resonators can enhance light-matter interaction, modify intrinsic molecular properties such as radiative emission rates, and create new molecule-photon hybrid quantum states. To date, corresponding implementations are based on electronic transitions in the visible spectral region with large transition dipoles yet hampered by fast femtosecond electronic dephasing. In contrast, coupling molecular vibrations with their weaker dipoles to infrared optical resonators has been less explored, despite long-lived coherences with 2 orders of magnitude longer dephasing times...
September 19, 2018: ACS Photonics
Sotiris Droulias, Thomas Koschny, Costas M Soukoulis
The quest for subwavelength coherent light sources has recently led to the exploration of dark-mode based surface lasers, which allow for independent adjustment of the lasing state and its coherent radiation output. To understand how this unique design performs in real experiments, we need to consider systems of finite size and quantify finite-size effects not present in the infinite dark-mode surface laser model. Here we find that, depending on the size of the system, distinct and even counterintuitive behavior of the lasing state is possible, determined by a balanced competition between multiple loss channels, including dissipation, intentional out-coupling of coherent radiation, and leakage from the edges of the finite system...
September 19, 2018: ACS Photonics
Gerold V Kristanz, Nikita Arnold, Alexander V Kildishev, Thomas A Klar
Spasers and nanolasers produce a significant amount of heat, which impedes their realizability. We numerically investigate the farfield emission and thermal load in optically pumped spasers with a coupled electromagnetic/thermal model, including additional temperature discontinuities due to interfacial Kapitza resistance. This approach allows to explore multiple combinations of constitutive materials suitable for robust manufacturable spasers. Three main channels of heat generation are quantified: metal absorption at pumping and spasing wavelengths and nonradiative relaxations in the gain material...
September 19, 2018: ACS Photonics
Annalisa Brodu, Mariana V Ballottin, Jonathan Buhot, Elleke J van Harten, Dorian Dupont, Andrea La Porta, P Tim Prins, Mickael D Tessier, Marijn A M Versteegh, Val Zwiller, Sara Bals, Zeger Hens, Freddy T Rabouw, Peter C M Christianen, Celso de Mello Donega, Daniel Vanmaekelbergh
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...
August 15, 2018: ACS Photonics
Yuyang Wang, Peter Zijlstra
We present a numerical study on plasmon-enhanced single-molecule enzymology. We combine Brownian dynamics and electromagnetic simulations to calculate the enhancement of fluorescence signals of fluorogenic substrate converted by an enzyme conjugated to a plasmonic particle. We simulate the Brownian motion of a fluorescent product away from the active site of the enzyme, and calculate the photon detection rate taking into account modifications of the excitation and emission processes by coupling to the plasmon...
August 15, 2018: 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
Anton Kuzyk, Ralf Jungmann, Guillermo P Acuna, Na Liu
The specificity and simplicity of the Watson-Crick base pair interactions make DNA one of the most versatile construction materials for creating nanoscale structures and devices. Among several DNA-based approaches, the DNA origami technique excels in programmable self-assembly of complex, arbitrary shaped structures with dimensions of hundreds of nanometers. Importantly, DNA origami can be used as templates for assembly of functional nanoscale components into three-dimensional structures with high precision and controlled stoichiometry...
April 18, 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
Rebeca Sola-Llano, Yasuhiko Fujita, Luis Gómez-Hortigüela, Almudena Alfayate, Hiroshi Uji-I, Eduard Fron, Shuichi Toyouchi, Joaquín Pérez-Pariente, Iñigo López-Arbeloa, Virginia Martínez-Martínez
A cyanine dye (PIC) was occluded into two 1D-nanopoporus Mg-containing aluminophosphates with different pore size (MgAPO-5 and MgAPO-36 with AFI and ATS zeolitic structure types, with cylindrical channels of 7.3 Å diameter and elliptical channels of 6.7 Å × 7.5 Å, respectively) by crystallization inclusion method. Different J-aggregates are photophysically characterized as a consequence of the different pore size of the MgAPO frameworks, with emission bands at 565 nm and at 610 nm in MgAPO-5 and MgAPO-36, respectively...
January 17, 2018: ACS Photonics
Richard Liu, Richard Schaller, Chang Qiang Chen, Can Bayram
Ultraviolet emission characteristics of cubic (c-) GaN enabled through hexagonal-to-cubic phase transition are reported. Substrate patterning and material growth are shown to affect phase purity and emission characteristics of c-GaN as studied by electron backscatter diffraction, and photo- and cathodoluminescence, respectively. Raman study shows a tensile strain in the c-GaN. Time-resolved photoluminescence reveals c-GaN band edge emission decay time of 11 ps. The ultraviolet emissions from both phases of GaN are linearly polarized in the same direction, which is along the ⟨112̅0⟩ and ⟨110⟩ directions of hexagonal GaN and c-GaN, respectively...
2018: ACS Photonics
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