Phonon-Plasmon Interaction in Metal-Insulator-Metal Localized Surface Plasmon Systems

We investigate theoretically and numerically the coupling between elastic and localized surface plasmon modes in a system of gold nanocylinders separated from a thin gold film by a dielectric spacer of few nanometers thickness. That system supports plasmon modes confined in between the bottom of the nanocylinder and the top of the gold film, which arise from the formation of interference patterns by short-wavelength metal-insulator-metal propagating plasmon. First we present the plasmonic properties of the system though computer-simulated extinction spectra and field maps associated to the different optical modes. Next a simple analytical model is introduced, which allows to correctly reproduce the shape and wavelengths of the plasmon modes. This model is used to investigate the efficiency of the coupling between an elastic deformation and the plasmonic modes. In the last part of the paper, we present the full numerical simulations of the phononic properties of the system, and then compute the acousto-plasmonic coupling between the different plasmon modes and five acoustic modes of very different shape. The efficiency of the coupling is assessed first by evaluating the modulation of the resonance wavelength, which allows comparison with the analytical model, and finally in term of time-modulation of the transmission spectra on the full visible range, computed for realistic values of the deformation of the nanoparticle.Comment: 12 pages, 9 figure

Angular plasmon response of gold nanoparticles arrays: approaching the Rayleigh limit

AbstractThe regular arrangement of metal nanoparticles influences their plasmonic behavior. It has been previously demonstrated that the coupling between diffracted waves and plasmon modes can give rise to extremely narrow plasmon resonances. This is the case when the single-particle localized surface plasmon resonance (λLSP) is very close in value to the Rayleigh anomaly wavelength (λRA) of the nanoparticles array. In this paper, we performed angle-resolved extinction measurements on a 2D array of gold nano-cylinders designed to fulfil the condition λRA<λLSP. Varying the angle of excitation offers a unique possibility to finely modify the value of λRA, thus gradually approaching the condition of coupling between diffracted waves and plasmon modes. The experimental observation of a collective dipolar resonance has been interpreted by exploiting a simplified model based on the coupling of evanescent diffracted waves with plasmon modes. Among other plasmon modes, the measurement technique has also evidenced and allowed the study of a vertical plasmon mode, only visible in TM polarization at off-normal excitation incidence. The results of numerical simulations, based on the periodic Green's tensor formalism, match well with the experimental transmission spectra and show fine details that could go unnoticed by considering only experimental data

Modele atomique simple d'heterostructure metallique

SIGLECNRS t b / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Effect of graphene layer on the localized surface plasmon resonance (LSPR) and the sensitivity in periodic nanostructure

International audienceWe study the interaction of gold nanoparticles with a graphene film. Graphene is used as a spacer, as thin as possible, between the gold nanoparticles and the detection dielectric medium, and one of the advantages of graphene is to protect the structure, which allows to avoid the oxidation of nanoparticles. We focus our study on the variation of the resonant structure (LSPR) depending on the thickness of the graphene layer (0.34-5 nm). A stronger resonance behavior of positions in the absorption spectrum shows a strong coupling between the LSP on gold nanoparticles and the covering film. Numerical simulations indicate a significant shift of the resonance wavelength structure SiOx/AuNPs/Graphene/SiOx (657.90 nm) compared with experimental results obtained on SiOx/AuNPs/SiOx (574.71 nm) and optimized for the required parameters proposed LSPR system we achieve the highest detection sensitivity range, while the location of points of the electric field on the best corners of the gold-graphene nanoparticles

Modélisation des structures nano-plasmoniques et photoniques (applications aux phénomènes de filtrage et à la conception de capteurs bioplasmoniques)

Ce travail porte sur la modélisation et simulation avec la méthode des différences finies (FDTD) de structures plasmonique et photoniques à l échelle submicronique. Dans une première partie, nous avons modélisé la propagation des ondes électromagnétiques à travers des nano-guides diélectriques (air ou SiO2), pris en sandwich entre deux plaques métalliques (de type Metal-Isolant-Metal). L excitation des plasmons-polaritons aux interfaces permet le guidage d ondes lumineuses à une échelle sub-longueur d onde. Nous avons étudié les propriétés de guidage dans le domaine du visible et de l infrarouge proche, notamment le couplage du guide avec des nano-résonateurs en vue d explorer des fonctionnalités telles que le filtrage sélectif ou par réjection ainsi que des dispositifs de démultiplexage. Ces mêmes propriétés ont été étudiées dans une structure photonique submicronique constituée de guides d ondes d InP entouré d air, couplé à un ensemble de cavités. Ces nano et microstructures constituent les briques de base pour la conception de nouveaux circuits intégrés tout-optique. Dans une seconde partie de la thèse, on s est intéressé à la modélisation de l interaction des ondes électromagnétiques avec des nanoparticules d or déposées sur un substrat de SiO2, et recouvertes d une couche d un matériau diélectrique. Ce type de structures est prometteur pour réaliser des nano-capteurs bioplasmoniques en vue de caractériser des produits biologiques déposés en faible quantité sur la surface du diélectrique. Nous avons montré que la fréquence de la réponse plasmonique des particules présente une variation oscillatoire périodique en fonction l épaisseur du diélectrique, avec une amplitude des oscillations qui peut atteindre quelques dizaines de nanomètres. Nous avons étudié ce phénomène en fonction des paramètres géométriques des nanoparticules d or et de l indice du diélectrique qui les recouvrent. L objectif est de comprendre comment ces paramètres influencent la gamme de fréquence plasmonique ainsi que la sensibilité du détecteur. Ce travail théorique a été confronté aux résultats expérimentaux réalisés par l équipe Bio-Interfaces de L IRI (Institut de recherche interdisciplinaire, Lille 1).This work concerns the modeling and simulation by the finite difference method (FDTD) of plasmonic and photonic structures at the submicron scale. In the first part of the thesis we studied the propagation of electromagnetic-waves through two different dielectric nanoscale waveguides (made out of air and SiO2), sandwiched between two metallic plates (Metal-insulator-Metal). The excitation of surface plasmon-polariton at the interfaces of such waveguides enables light waveguiding at the subwavelength domain. We did study the waveguiding properties in the visible and near infrared ranges of frequency. Coupling of the main waveguide with a nano-resonatorwas investigated to achieve optical operations as filtering (in rejection and selection) and demultiplexing. These same optical functionalities were studied in a submicron photonic structure which is constituted by waveguides of InP surrounded by air, coupled to several cavities. Such nano and microstructures are essential for the design of new all-optical integrated circuits. The second part of the thesis concerns modeling of electromagnetic-waves interaction with metallic (gold) nanoparticles deposited on a glass substrate (SiO2) and covered with a dielectric layer. These structures are promising for the conception of plasmonic nanosensors, which would be used to characterize small amount of biological molecules deposited on the dielectric layer surface. We have shown that the frequency of the plasmonic resonance of metallic particles exhibits an oscillatory variation with the thickness of the layer, with an amplitude reaching tens of nanometers. One investigated this phenomenon according to geometrical parameters of the gold particles and the refractive index of the dielectric layer covering the particles. The aim of such study is to understand how the physical and geometrical parameters influence the frequency range of the plasmonic resonance of the particles and the sensitivity of the nanosensor. This theoretical work was confronted with experimental results realized by Bio-interfaces team of IRI (Interdisciplinary institute of research, University of Lille 1).LILLE1-Bib. Electronique (590099901) / SudocSudocFranceF

Long-lived resonances: photonic triangular pyramid

International audienceNew bound in continuum states and long-lived resonances in one photonic triangular pyramid with two semi-infinite leads are reported, together with general theorems giving their existence conditions. The pyramid is composed of connected open loops (of length L). When bound in continuum states exist within state continua, they induce long-lived resonances for specific values of some modified lengths of the 6 open loops constituting the pyramid. This enables to tune these resonances by means of these lengths. The results obtained in this work take due account of the state number conservation between the final system and the reference one constituted by the independent pyramid and semi-infinite leads. The respect of this conservation enables to find all the states of the final system and among them the bound in continuum ones. This is one of the originalities of this work. The other new general results are the different sets of bound in continuum states and long-lived resonances, as well as the theorems giving their existence conditions. These results may have a big impact on general investigations of bound in continuum states, long-lived resonances and communication technology improvements

Effect of MoS2 layer on the LSPR in periodic nanostructures

International audienceIn this work, we propose a new configuration of the localized surface plasmon resonance (LSPR), based on MoS2 hybrid structures for ultrasensitive biosensing applications. The plasmonic resonances are widely used in bimolecular detection and continue to be an active network because of the rich variety of surface configurations and measurement donations. The present work studies the interaction of gold nanoparticles with a MoS2 film. MoS2 is used as a thin spacer between the gold nanoparticles and the dielectric medium used for detection. MoS2 monolayers have emerged recently as promising nanostructures for various applications in both the optics and electronics. This paper gives an overview of the optical properties of 2D nanostructures based on this new class of materials. A stronger behavior of the resonance positions in the absorption spectrum exhibits a strong coupling between the LSPR on the gold nanoparticles and the MoS2 coating film. Numerical simulations display a significant red shift of the plasmonic resonance (lambda(max)) and the results show that using a 3.90 nm MoS2 layer, the plasmon resonance wavelength is increased of 333.7 nm. We also study the performance of the proposed biosensors in terms of sensitivity using multilayers of MoS2, and normal incidence to the surface of SiOx/AuNPs/MoS2/water and SiO/MoS2/AuNPs/water. We obtain a very high sensitivity of 297.62 nm/RIU corresponding to an increase of 26% compared to the results obtained on SiOx/AuNPs/water, with a location of the electric field on the gold nanoparticles and the covering MoS2 layer. These characteristics should make these biosensors a preferred choice for detection applications

MoS₂-graphene hybrid nanostructures enhanced localized surface plasmon resonance biosensors

International audienceWe propose a new configuration of a localized surface plasmon resonance (LSPR) biosensor that is based on MoS2-graphene hybrid structures for ultrasensitive detection of molecules. The performance parameters of the proposed biosensor are defined in terms of absorption and sensitivity. Our study show that sensitivity can be greatly increased either by adding a bilayer MoS2/graphene on the Au nanoparticles or by adding the MoS2 layer or the graphene layer on the surface of the Au nanoparticles. The absorption curves for the proposed LSPR biosensor are analyzed and compared with the conventional biosensors without MoS2/graphene. By optimizing the structure of the sensor, we find that the sensitivity as high as 360 nm/RIU can be achieved with 8-layers of MoS2 and 10-layers of graphene. In addition, we show that the sensitivity can be controlled by changing the number of the monolayer of MoS2 and/or graphene. Finally, we show that this sensor can detect successfully impure water after absorption of target single-stranded DeoxyriboNucleic Acid (ssDNA) biomolecules

Performance evaluation of multifunctional SPR bimetallic sensor using hybrid 2D-nanomaterials layers

International audienceIn this paper, we analyzed the sensing performance of the multifunctional surface plasmon resonance (SPR) biosensors based on bimetallic film (Ag/Al2O3), and a hybrid nanostructure of BaTiO3 and 2D nanomaterials (Ti3C2T, black phosphorus and BlueP/MoS2 heterostructure). Using excitation light at 633 nm, we numerically analyze performance such as angular sensitivity, peak sensitivity, figure of merit, and electric field strength. The study shows the proposed biosensor design exhibits a highest sensitivity of 504 deg/RIU with a 320% improvement over the conventional SPR sensor reported so far on similar 2D nanomaterials, and can also maintain a good quality SPR curve. The results of different proposed and optimized nano-configurations show that the improved angular sensitivity of 120%, 60%, 290% and 80% for BaTiO3, Ti3C2T, Black phosphorus and BlueP/MoS2, respectively, for a change in the refractive index (RI) of the sensing medium of RIU. Similarly, the variation in field intensity at the sensing interface further confirms the high sensitivity obtained for our proposed SPR biosensor. Therefore, our proposed design would be practically suitable for biosensing with higher performance with the available fabrication technologies