Magnetic Mode Coupling in Hyperbolic Bowtie Meta-Antennas

Hyperbolic metaparticles have emerged as the next step in metamaterial applications, providing tunable electromagnetic properties on demand. However, coupling of optical modes in hyperbolic meta-antennas has not been explored. Here, we present in detail the magnetic and electric dipolar modes supported by a hyperbolic bowtie meta-antenna and clearly demonstrate the existence of two magnetic coupling regimes in such hyperbolic systems. The coupling nature is shown to depend on the interplay of the magnetic dipole moments, controlled by the meta-antenna effective permittivity and nanogap size. In parallel, the meta-antenna effective permittivity offers fine control over the electrical field spatial distribution. Our work highlights new coupling mechanisms between hyperbolic systems that have not been reported before, with a detailed study of the magnetic coupling nature, as a function of the structural parameters of the hyperbolic meta-antenna, which opens the route toward a range of applications from magnetic nanolight sources to chiral quantum optics and quantum interfaces

Plasmon-enhanced second harmonic sensing

It has been recently suggested that the nonlinear optical processes in plasmonic nanoantennas allow for a substantial boost in the sensitivity of plasmonic sensing platforms. Here we present a sensing device based on an array of non-centrosymmetric plasmonic nanoantennas featuring enhanced second harmonic generation (SHG) integrated in a microfluidic chip. We evaluate its sensitivity both in the linear and nonlinear regime using a figure of merit (FOM = $(\Delta I/I)/\Delta n$) that accounts for the relative change in the measured intensity, \textit{I}, against the variation of the environmental refractive index \textit{n}. While the signal-to-noise ratio achieved in both regimes allows the detection of a minimum refractive index variation $\Delta n_{min} \approx 10^{-3}$, the platform operation in the nonlinear regime features a sensitivity (i.e. the FOM) that is at least 3 times higher than the linear one. Thanks to the surface sensitivity of plasmon-enhanced SHG, our results show that the development of such SHG sensing platforms with sensitivity performances exceeding those of their linear counterparts is within reach.Comment: 19 Pages, 5 Figure

Two-photon photopolymerization directly initiated by spiropyran photochromic molecules

Here, we report the ability of spiropyrans to initiate two-photon polymerization (TPP) for the first time in the literature. The comparison and synergies between the spiropyran photochromic molecule of interest, namely 6-nitro-BIPS, and well-known photoinitiators of radical photopolymerization have been studied. The spiropyran (SPy) molecule can initiate TPP in the presence of trifunctional acrylic monomers and create true 3D structures. The comparison with Irgacure 819, a well-known Type-I photoinitiator, shows that SPy has a comparable capability for TPP. In addition, the combination of SPy with methyl diethanolamine increased the reactivity of both one- and two-photon polymerizations. In the last section, we discuss which SPy isomer is the active photochromic species capable of generating radicals for initiating two-photon polymerization

Molecular Plasmonics or how to control plasmons with molecules (and vice versa)

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Composants plasmoniques passifs et actifs

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Conception, réalisation et caractérisation de cristaux plasmoniques (application au contrôle de la propagation d ondes optiques de surface)

Un cristal plasmonique consiste en un film métallique structuré périodiquement. Les cristaux plasmoniques uni- et bidimensionnels étudiés dans cette étude sont fabriqués par lithographie par faisceau d électrons et caractérisés par microscopie de champ proche (PSTM). Dans le cas unidimensionnel, des miroirs de Bragg plasmoniques sont intégrés à un film métallique ainsi qu à un ruban métallique permettant la déflexion à 90 de la direction de propagation du plasmon de surface. Dans le cas bidimensionnel, un réseau de plots d or déposé sur un film métallique est étudié pour deux directions d incidence du plasmon. L existence de bandes interdites photoniques est mise en évidence et l influence du facteur de remplissage sur ces dernières est étudié. Le confinement et le guidage du plasmon de surface dans un canal ouvert dans ce cristal est expliqué pour les deux directions d incidence et l étude du guidage le long d un canal présentant un virage est ensuite réalisée.A periodic modulation of a metallic film which sustains a surface plasmon polariton (SPP) is called a plasmonic crystal (PC). In this work, one and two dimensional PC are fabricated by electron beam lithography and characterized by Photon Scanning Tunneling Microscope. In the one dimensional case, Plasmonic Bragg Mirrors (PBM) are added first to a metallic film and then to a metallic stripe allowing the deflexion of the SPP propagation with a angle of 90. In the two dimensional case, a triangular lattice of gold bumps is deposited on a metallic film. The interaction of this PC with the SPP is studied for two different incident propagation axes. The photonic band gap effect and the influence of the filling factor are characterized. The guiding mechanisms of the SPP in channel defects opened in PC are explained by means of Ewald constructions and the SPP propagation in channels including bends is observed.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

Conception, réalisation et caractérisation de cristaux plasmoniques (application au contrôle de la propagation d ondes optiques de surface)

Un cristal plasmonique consiste en un film métallique structuré périodiquement. Les cristaux plasmoniques uni- et bidimensionnels étudiés dans cette étude sont fabriqués par lithographie par faisceau d électrons et caractérisés par microscopie de champ proche (PSTM). Dans le cas unidimensionnel, des miroirs de Bragg plasmoniques sont intégrés à un film métallique ainsi qu à un ruban métallique permettant la déflexion à 90 de la direction de propagation du plasmon de surface. Dans le cas bidimensionnel, un réseau de plots d or déposé sur un film métallique est étudié pour deux directions d incidence du plasmon. L existence de bandes interdites photoniques est mise en évidence et l influence du facteur de remplissage sur ces dernières est étudié. Le confinement et le guidage du plasmon de surface dans un canal ouvert dans ce cristal est expliqué pour les deux directions d incidence et l étude du guidage le long d un canal présentant un virage est ensuite réalisée.A periodic modulation of a metallic film which sustains a surface plasmon polariton (SPP) is called a plasmonic crystal (PC). In this work, one and two dimensional PC are fabricated by electron beam lithography and characterized by Photon Scanning Tunneling Microscope. In the one dimensional case, Plasmonic Bragg Mirrors (PBM) are added first to a metallic film and then to a metallic stripe allowing the deflexion of the SPP propagation with a angle of 90. In the two dimensional case, a triangular lattice of gold bumps is deposited on a metallic film. The interaction of this PC with the SPP is studied for two different incident propagation axes. The photonic band gap effect and the influence of the filling factor are characterized. The guiding mechanisms of the SPP in channel defects opened in PC are explained by means of Ewald constructions and the SPP propagation in channels including bends is observed.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

Revealing the Hidden Plasmonic Modes of a Gold Nanocylinder

International audienceA metallic nanocylinder is one of the most studied simple plasmonic nanostructures. Due to its internal symmetry, it can sustain different modes, but the majority of the studies focus on the horizontal dipolar resonance. Studying the whole variety of the excited modes in an individual nanocylinder is crucial to the development of further applications. Herein, we analyze the modes excited in a single gold nanocylinder on a glass substrate with standard optical characterization techniques and numerical simulations. The analysis of the scattering radiation patterns of the different modes shows that specific collection geometries are required to distinguish them. We propose a new method to record the hidden modes using a conventional dark-field scattering microscope, and for the first time, we show how the vertical dipolar mode of a single nanocylinder can be revealed optically

Hidden modes of a plasmonic nano-object

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