Dispersed and encapsulated gain medium in plasmonic nanoparticles: a multipronged approach to mitigate optical losses.
ABSTRACT The performance of all metamaterial-based applications is significantly limited by the inherent and strong energy dissipation present in metals, especially in the visible range. In fact, these materials suffer from rather strong damping of the plasmon fields which can become obstructive for most optical and photonic applications. Therefore, eliminating losses in optical metamaterials is critical for enabling their numerous potential applications. We experimentally demonstrate that the incorporation of gain material (fluorophores) in the high-local-field areas of a metamaterial subunits (gold core/silica shell nanoparticles) makes it possible to induce resonant energy transfer processes from gain units to plasmonic nanoparticles. A comparison between gain-assisted (nanoparticle-dye dispersion) and gain-functionalized (dye encapsulated into the shell) systems is reported. Fluorescence quenching and time-resolved spectroscopy along with modification of Rayleigh scattering and transmission of a probe beam as a function of impinging energy are key evidence of the strong coupling occurring between NPs and gain medium. The multipronged approach used to compensate losses in these metal-based subunits permits one to obtain important advances in materials science and paves the way toward further promising scientific research aimed to enable the wide range of electromagnetic properties of optical metamaterials.
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ABSTRACT: The performance of all metamaterial-based applications is significantly limited by the inherent and strong energy dissipation present in metals, especially in the visible range. We experimentally demonstrate that the incorporation of excitonic material (chromophores) in the high-local-field areas of plasmon nanostructures induce coherent resonant energy transfer processes from chromophores (donors) to plasmon nanoentities (acceptors). Ultra-fast fluorescent time-resolved spectroscopy paired with transient absorption spectroscopy and spectroscopic ellipsometry in pump-probe configuration emphasize a strong exciton-plasmon coupling behind the process of non-radiative excitation energy transfer (RET). Across scales studies show how these energy transfer processes occurring at the nanoscale translate to bulk materials. Multipronged strategies – bio-inspired and bottom up -allowed obtaining important advances in materials science and paves the way toward further promising scientific research aimed to enable the wide range of electromagnetic properties of optical metamaterials. I. INTRODUCTION The main aim of this work is to propose a multi-scale approach to address the fundamental problem of optical losses in engineered metallo-dielectric nanostructures by coupling them with fluorophores to promote effective resonant excitation energy transfer, that eventually leads to super-radiant modes and laser action. In fact, it is well known that these materials suffer from a rather strong damping of the plasmon fields which can become obstructive for most optical and photonic applications. The influence of a gain medium on Surface Plasmon-Polariton (SPP) propagation and loss compensation in metallic nanostructures has been receiving more and more attention over the past years, especially with the rise of nano-photonics. Several scientists have demonstrated, theoretically and experimentally, that the losses associated with plasmon resonances could efficiently be reduced via non-radiative energy transfers by the nearby presence of suitable gain media [1-6]. This transfer of energy from a gain component to plasmonic elements is the key concept that we implemented to reduce losses in the designed nanostructures, opening the way to very promising opto-plasmonic applications. Therefore, eliminating losses in optical nanostructures is critical for enabling their numerous potential applications.8th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics – Metamaterials 2014; 09/2014
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ABSTRACT: The polarization-dependent properties of electromagnetic plane wave scattering from active cylindrical coated nano-particle (C-CNP) antennas are investigated in the visible frequency band. It is demonstrated with three independent orthogonal polarizations that the dipole mode is excited resonantly in each case, even though the resonant size of the particles, as seen by these normally incident plane waves, is different. Moreover, the scattering behaviors for various angles of incidence are studied. It is shown that the polarization state along the main axis of the cylinder dominates the scattering properties of these resonant, active C-CNP’s; and because of the natural symmetry, they mainly depend on the elevation angle α and not the azimuth angle β.Journal of Electromagnetic Waves and Applications 07/2013; 27(11):1392-1406. · 1.40 Impact Factor
- IEEE Journal of Selected Topics in Quantum Electronics 07/2015; 21(4):1-12. · 3.47 Impact Factor