Literatura científica selecionada sobre o tema "Modal plasmonic cavities"

We survey expressions of the effective modal volume, Veff, commonly used in the literature for nanoscale photonic and plasmonic cavities. We apply different expressions of Veff to several canonical cavities designed for nanoscale near-infrared light sources, including metallo-dielectric and coaxial geometries. We develop a metric for quantifying the robustness of different Veff expressions to the different cavities and materials studied. We conclude that no single expression for Veff is universally applicable. Several expressions yield nearly identical results for cavities with well-confined photonic-type modes. For cavities with poor confinement and a low quality factor, however, expressions using the proper normalization method need to be implemented to adequately describe the diverging behavior of their effective modal volume. The results serve as a practical guideline for mode analysis of nanoscale optical cavities, which show promise for future sensing, communication, and computing platforms.

In contrast to the high performances of long-range, high-speed optical information transfer, optical information processing remains outperformed by electronic microprocessing. The two mains reasons are the lack of gain medium that hampers the development of an optical analogue of the transistor and the lack of compactness of the approaches proposed so far. Here, we demonstrate a new concept of the design of all-optical elementary computing units based on the shaping of plasmonic modal landscape in micrometric on-chip 2D cavities to realize reconfigurable Arithmetic and Logic Units (ALU). Our interconnect-free devices perform multi-bit logic gate functions in a single cavity without ALU cascading, therefore obviating loss in vias and so the need for gain to restore the binary signal. Moreover, an astute cavity design allows to reconfigure a single cavity into multiple logic functions, including a first full adder. The main challenge on the way to increasing the functional Boolean complexity is the design of the cavity shape and of the excitation/detection parameters for which an approach based on artificial intelligence will be implemented.

AbstractIn this work we present a simple transfer-matrix based modeling tool for arbitrarily layered stacks of resonant plasmonic metasurfaces interspersed with dielectric and metallic multilayers. We present the application of this model by analyzing three seminal problems in nanophotonics. These are the scenario of perfect absorption in plasmonic Salisbury screens, strong coupling of microcavity resonances with the resonance of plasmon nano-antenna metasurfaces, and the hybridization of cavities, excitons and metasurface resonances.

AbstractWe report measurements of the optical transmission through a plasmonic flat surface interferometer. The transmission spectrum shows Fabry-Perot-like modes, where for each mode order, the maximal transmission occurs at a gap that grows linearly with wavelength, giving the appearance of diagonal dependence on gap and wavelength. The experimental results are supported by numerical solutions of the wave equations and by a simplified theoretical model that is based on the coupling between localized and propagating surface plasmon. This work explains not only the appearance of the modes but also their sharp dependence on the gap, taking into consideration the refractive indices of the surrounding media. The transmission spectra provide information about the phase difference between the light impinging on the two cavities, enabling interferometric measurement of the light phase by transmission through the coupled plasmonic cavities. The 1° phase-difference resolution is obtained without any propagation distance, thus making this interferometer suitable for on-chip operation.

The surface-enhanced Raman scattering (SERS) of molecular species in plasmonic cavities can be described as an optomechanical process where plasmons constitute an optical cavity of reduced effective mode volume which effectively couples to the vibrations of the molecules. An optomechanical Hamiltonian can address the full quantum dynamics of the system, including the phonon population build-up, the vibrational pumping regime, and the Stokes–anti-Stokes correlations of the photons emitted. Here we describe in detail two different levels of approximation to the methodological solution of the optomechanical Hamiltonian of a generic SERS configuration, and compare the results of each model in light of recent experiments. Furthermore, a phenomenological semi-classical approach based on a rate equation of the phonon population is demonstrated to be formally equivalent to that obtained from the full quantum optomechanical approach. The evolution of the Raman signal with laser intensity (thermal, vibrational pumping and instability regimes) is accurately addressed when this phenomenological semi-classical approach is properly extended to account for the anti-Stokes process. The formal equivalence between semi-classical and molecular optomechanics descriptions allows us to describe the vibrational pumping regime of SERS through the classical cross sections which characterize a nanosystem, thus setting a roadmap to describing molecular optomechanical effects in a variety of experimental situations.

AbstractHybrid cavity-antenna systems have been proposed to combine the sub-wavelength light confinement of plasmonic antennas with microcavity quality factors Q. Here, we examine what confinement and Q can be reached in these hybrid systems, and we address their merits for various applications in classical and quantum optics. Specifically, we investigate their applicability for quantum-optical applications at noncryogenic temperatures. To this end we first derive design rules for hybrid resonances from a simple analytical model. These rules are benchmarked against full-wave simulations of hybrids composed of state-of-the-art nanobeam cavities and plasmonic-dimer gap antennas. We find that hybrids can outperform the plasmonic and cavity constituents in terms of Purcell factor, and additionally offer freedom to reach any Q at a similar Purcell factor. We discuss how these metrics are highly advantageous for a high Purcell factor, yet weak-coupling applications, such as bright sources of indistinguishable single photons. The challenges for room-temperature strong coupling, however, are far more daunting: the extremely high dephasing of emitters implies that little benefit can be achieved from trading confinement against a higher Q, as done in hybrids. An attractive alternative could be strong coupling at liquid nitrogen temperature, where emitter dephasing is lower and this trade-off can alleviate the stringent fabrication demands required for antenna strong coupling. For few-emitter strong-coupling, high-speed and low-power coherent or incoherent light sources, particle sensing and vibrational spectroscopy, hybrids provide the unique benefit of very high local optical density of states, tight plasmonic confinement, yet microcavity Q.

Abstract The constant need to miniaturize technological devices has increased the development of novel optical devices in the nanoscale. A common kind of photonic devices are built using Metal-Insulator-Metal (MIM) interfaces to generate Surface Plasmons Polaritons (SPPs) and process light waves in the optical window. In this paper a 12 channel demultiplexer is proposed using 8 cavities coupled to both sides of the main waveguide. Then the nano demultiplexer is modelled in COMSOL Multiphysics using Drude model and Johnson and Christy parameters for the optical constants. Then we compare the transmission spectrum from 400 to 2200 nm for both models and discuss the differences advantages of each method.

In order to reduce the size of the device and realize the ultrafast response time and dynamic tunableness, the single-band and dual-band plasmon induced transparency (PIT) effect are investigated based on graphene nanoribbon waveguide side-coupled rectangle cavity. The slow light properties of the model are analyzed numerically and theoretically by coupled mode theory and finite difference time domain method. With controlling the chemical potential of the graphene rectangle cavity, the tunability of the resonant wavelength and the transmission peak can be achieved simultaneously in single-band and dual-band PIT model. As the chemical potential of graphene increases, the resonant wavelength of each transmission window of PIT effect decreases gradually and presents the blue shift. In addition, through dynamically tuning the resonant wavelength of the graphene rectangle cavity, when the chemical potential of the graphene rectangle cavity increases from 0.41 to 0.44 eV, the group index of single PIT system is controlled to be between 79.2 and 28.3, and the tunable bandwidth is 477 nm. Moreover, the group index of dual PIT system is controlled to be between 143.2 and 108.6 when the chemical potentials of graphene rectangle cavities 1, 2, and 3 are 0.39–0.42 eV, 0.40–0.43 eV, and 0.41–0.44 eV, respectively. The size of the entire PIT structure is <0.5 μm². The research results here in this work are of reference significance in designing and fabricating the optical sensors, optical filters, slow light and light storage devices with ultrafast, ultracompact and dynamic tunableness.

Ce travail de thèse est consacré à l'étude détaillée de la photoluminescence non linéaire émise par des microcavités plasmoniques modales en or. Aujourd’hui encore, l’origine de cette émission lumineuse secondaire fait débat et de nombreuses recherches tentent d’identifier les mécanismes physiques impliqués. Nos résultats démontrent sans ambiguïté le rôle de la dynamique thermique du bain d'électrons chauds, généré par l'absorption d'impulsions laser femtosecondes, dans le processus d'émission non linéaire. Ce travail de thèse est consacré à l'étude détaillée de la photoluminescence non linéaire émise par des microcavités plasmoniques modales en or. Aujourd’hui encore, l’origine de cette émission lumineuse secondaire fait débat et de nombreuses recherches tentent d’identifier les mécanismes physiques impliqués. Nos résultats démontrent sans ambiguïté le rôle de la dynamique thermique du bain d'électrons chauds, généré par l'absorption d'impulsions laser femtosecondes, dans le processus d'émission non linéaire
This thesis work is devoted to the detailed study of nonlinear photoluminescence emitted by gold modal plasmonic microcavities. Even today, the origin of this secondary light emission is debated, and numerous research attempts to identify the physical mechanisms involved. Our results unambiguously demonstrate the predominant role of the thermal dynamics of the hot electrons bath, generated by the absorption of femtosecond laser pulses, in the nonlinear emission process. Furthermore, our work shows that this secondary emission of light is intrinsically linked to the rich plasmonic landscape offered by this type of structures. We therefore propose several methods based on electrical and optical controls to redistribute the generation of nonlinear photoluminescence within the plasmonic cavity. Finally, these results allowed us to develop an all-optical reconfigurable logic gate capable of performing simple arithmetic and logic operations

L'objectif principal de cette thèse est de concevoir, fabriquer et caractériser les dispositifs plasmoniques basés sur les cavités métalliques bidimensionnelles monocristallines pour le transfert d'information et la réalisation d'opérations logiques. Les fonctionnalités ciblées émergent de l'ingénierie spatiale et spectrale de résonances plasmon d'ordre supérieur supportées par ces cavités prismatiques. Les nouveaux éléments étudiés dans cette thèse ouvrent la voie à de nouvelles stratégies de transfert et de traitement de l'information en optique intégrée et miniaturisée. Dans un premier temps, nous caractérisons la réponse optique des nanoplaquettes d'or ultra-fines et de taille submicronique (400 à 900 nm) par spectroscopie en champ sombre. La dispersion des résonances plasmoniques d'ordre supérieur de ces cavités est mesurée et comparée avec un bon accord aux simulations obtenues par la méthode des dyades de Green (GDM). En outre, nous présentons une analyse par décomposition lorentzienne des réponses spectrales de ces nanoprismes déposés sur des minces substrats métalliques. Nous avons, par ailleurs systématiquement étudié les effets qui pourraient modifier les résonances plasmoniques par microscopie de luminescence non-linéaire, qui s'est avérée un outil efficace pour observer la densité d'états locale des plasmons de surface (SPLDOS). En particulier, nous montrons que les caractéristiques spectrale et spatiale des résonances plasmoniques d'ordre supérieur peuvent être modulées par la modification du substrat (diélectrique ou métallique), par l'insertion contrôlée d'un défaut dans la cavité ou par le couplage électromagnétique, même faible, entre les deux cavités. L'ingénierie rationnelle de la répartition spatiale des résonances confinées 2D a été appliquée à la conception de dispositifs à transmittance accordable entre deux cavités connectées. Les géométries particulières sont produites par gravure au faisceau d'ions focalisé sur des plaquettes cristallines d'or. Les dispositifs sont caractérisés par cartographie de luminescence non-linéaire en microscopie confocale et en microscopie de fuites. Cette dernière méthode offre un moyen unique d'observer la propagation du signal plasmon dans la cavité. Nous démontrons la dépendance en polarisation de la transmission plasmonique dans les composants à symétrie et géométrie adéquates. Les résultats sont fidèlement reproduits par notre outil de simulation GDM adapté à la configuration de transmission. Enfin, notre approche est appliquée à la conception et à la fabrication d'une porte logique reconfigurable avec plusieurs entrées et sorties. Nous démontrons que dix des douze portes logiques possibles à 2 entrées et 1 sortie sont activable sur une même structure en choisissant les trois points d'entrée et de sortie et en ajustant le seuil de luminescence non-linéaire pour le signal de sortie
The main objective of this PhD work is to design, fabricate and characterize plasmonic devices based on highly crystalline metallic cavities for the two-dimensional information transfer and logic gate operations. First, we thoroughly characterize the optical response of ultra-thin gold colloidal cavities of sub-micronic size (400 to 900 nm) by dark- field spectroscopy (Fig. 1a). The dispersion of the high order plasmonic resonances of the cavities is measured and compared with a good agreement to simulations obtained with a numerical based on the Green Dyadic Method (GDM). We further extend our experiments to systematically tune the spectral responses of these colloidal nanoprisms in vicinity of metallic thin film substrates. A comprehensive study of these sub-micronic size cavity in bowtie antenna configuration is performed. We show a polarization-dependent field enhancement and a nanoscale field confinement at specific locations in these bowtie antennas. We systematically study the effects that could potentially affect the plasmonic resonances by non-linear photon luminescence microscopy, which has proved to be an efficient tool to observe the surface plasmon local density of states (SPLDOS). Inparticular, we show that an effective spatially and spectrally tuning of the high order plasmonic resonances can be achieved by the modification of the substrate (dielectric or metallic), by the controlled insertion of a defect inside a cavity or by the weak electromagnetic coupling between two adjacent cavities. The rational tailoring of the spatial distribution of the 2D confined resonances was applied to the design of devices with tunable plasmon transmittance between two connected cavities. The specific geometries are produced by focused ion milling crystalline gold platelets. The devices are characterized by non-linear luminescence mapping in confocal and leakage radiation microscopy techniques. The latter offers a unique way to observe propagating SPP signal over a 2D plasmonic cavity. We demonstrate the polarization-dependent mode-mediated transmittance for devices withadequate symmetry. The results are faithfully reproduced with our simulation tool based on Green dyadic method. Finally, we extend our approach to the design and fabrication of a reconfigurable logic gate device with multiple inputs and outputs. We demonstrate that 10 out of the possible 12 2-input 1-output logic gates can be implemented on the same structure by choosing the two input and the one output points. We also demonstrate reconfiguration of the device by changing polarization of the incident beam, set of input locations and threshold of the non-linear luminescence readout signal