Transmission of plasmons through a nanowire

Exact quantitative understanding of plasmon propagation along nanowires is mandatory for designing and creating functional devices. Here we investigate plasmon transmission through top-down fabricated monocrystalline gold nanowires on a glass substrate. We show that the transmission through finite-length nanowires can be described by Fabry-P\'{e}rot oscillations that beat with free-space propagating light launched at the incoupling end. Using an extended Fabry-P\'{e}rot model, experimental and simulated length dependent transmission signals agree quantitatively with a fully analytical model.Comment: 5 pages, 4 figure

Electromechanically Tunable Suspended Optical Nano-antenna

Coupling mechanical degrees of freedom with plasmonic resonances has potential applications in optomechanics, sensing, and active plasmonics. Here we demonstrate a suspended two-wire plasmonic nano-antenna acting like a nano-electrometer. The antenna wires are supported and electrically connected via thin leads without disturbing the antenna resonance. As a voltage is applied, equal charges are induced on both antenna wires. The resulting equilibrium between the repulsive Coulomb force and the restoring elastic bending force enables us to precisely control the gap size. As a result the resonance wavelength and the field enhancement of the suspended optical nano-antenna (SONA) can be reversibly tuned. Our experiments highlight the potential to realize large bandwidth optical nanoelectromechanical systems (NEMS)

Driving plasmonic nanoantennas at perfect impedance matching using generalized coherent perfect absorption

Coherent perfect absorption (CPA) describes the absence of all outgoing modes from a lossy resonator, driven by lossless incoming modes. Here, we show that for nanoresonators that also exhibit radiative losses, e.g. plasmonic nanoantennas, a generalized version of CPA (gCPA) can be applied. In gCPA outgoing modes are suppressed only for a subset of (guided plasmonic) modes while other (radiative) modes are treated as additional loss channels - a situation typically referred to as perfect impedance matching. Here we make use of gCPA to show how to achieve perfect impedance matching between a single nanowire plasmonic waveguide and a plasmonic nanoantenna. Antennas with both radiant and subradiant characteristics are considered. We further demonstrate potential applications in back-ground-free sensing

Driving plasmonic nanoantennas at perfect impedance matching using generalized coherent perfect absorption

Coherent perfect absorption (CPA) describes the absence of all outgoing modes from a lossy resonator, driven by lossless incoming modes. Here, we show that for nanoresonators that also exhibit radiative losses, e.g., plasmonic nanoantennas, a generalized version of CPA (gCPA) can be applied. In gCPA outgoing modes are suppressed only for a subset of (guided plasmonic) modes while other (radiative) modes are treated as additional loss channels - a situation typically referred to as perfect impedance matching. Here we make use of gCPA to show how to achieve perfect impedance matching between a single nanowire plasmonic waveguide and a plasmonic nanoantenna. Antennas with both radiant and subradiant characteristics are considered. We further demonstrate potential applications in background-free sensing

Spectral-interference microscopy for characterization of functional plasmonic elements

Plasmonic modes supported by noble-metal nanostructures offer strong subwavelength electric-field confinement and promise the realization of nanometer-scale integrated optical circuits with well-defined functionality. In order to measure the spectral and spatial response functions of such plasmonic elements, we combine a confocal microscope setup with spectral interferometry detection. The setup, data acquisition, and data evaluation are discussed in detail by means of exemplary experiments involving propagating plasmons transmitted through silver nanowires. By considering and experimentally calibrating any setup-inherent signal delay with an accuracy of 1 fs, we are able to extract correct timing information of propagating plasmons. The method can be applied, e.g., to determine the dispersion and group velocity of propagating plasmons in nanostructures, and can be extended towards the investigation of nonlinear phenomena

Funktionelle plasmonische Nanoschaltkreise

In this work, functional plasmonic nanocircuitry is examined as a key of revolutionizing state-of-the-art electronic and photonic circuitry in terms of integration density and transmission bandwidth. In this context, numerical simulations enable the design of dedicated devices, which allow fundamental control of photon flow at the nanometer scale via single or multiple plasmonic eigenmodes. The deterministic synthesis and in situ analysis of these eigenmodes is demonstrated and constitutes an indispensable requirement for the practical use of any device. By exploiting the existence of multiple eigenmodes and coherence - both not accessible in classical electronics - a nanoscale directional coupler for the ultrafast spatial and spatiotemporal coherent control of plasmon propagation is conceived. Future widespread application of plasmonic nanocircuitry in quantum technologies is boosted by the promising demonstrations of spin-optical and quantum plasmonic nanocircuitry.In dieser Arbeit werden funktionelle plasmonische Schaltkreise als Schlüssel zur Revolutionierung modernster elektronischer und photonischer Schaltkreise in Bezug auf deren Integrationsdichte und Übertragungsbandbreite untersucht. Mit Hilfe numerischer Simulationen werden Bauelemente speziell für die Steuerung des Photonenflusses im Nanometerbereich mittels einzelner bzw. mehrerer plasmonischer Eigenmoden konzipiert. Die deterministische Synthese und Analyse solcher Eigenmoden wird aufgezeigt und stellt eine unverzichtbare Voraussetzung für die praktische Anwendung eines jeden Nanoschaltkreises dar. Durch die Existenz mehrerer Eigenmoden und Kohärenz - beide in der klassischen Elektronik nicht zugänglich - lässt sich ein nanoskaliger Richtkoppler für die ultraschnelle räumliche und räumlich-zeitliche kohärente Kontrolle der Plasmonenausbreitung entwerfen. Künftig werden plasmonische Schaltkreise aufgrund der vielversprechenden Demonstrationen von spinoptischen und quantenplasmonischen Schaltkreisen in Quantentechnologien weite Verbreitung finden