Dispersed and Encapsulated Gain Medium in Plasmonic Nanoparticles: a Multipronged Approach to Mitigate Optical Losses
CNR-IPCF Licryl Cosenza, Department of Physics, University of Calabria, 87036 Rende, Italy. ACS Nano
(Impact Factor: 12.88).
06/2011; 5(7):5823-9. DOI: 10.1021/nn2015562
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.
Available from: Iris Bell
- "The adaptive changes manifest via modulation of gene expression patterns, cytokine and inflammatory mediator release, immune system activation, neuronal effects, and biological signaling at the cell-to-cell level[81,76,80]. Cell uptake of silica NPs in the parts per billion (ppb) and parts per million (ppm) ranges occurs, and concentrations of various NPs in the ppb to ppm range can exert toxic effects on small organisms in the environment[153,154]. @BULLET Fifth, in contrast with ordinary bulk pharmaceutical drugs, NPs are uniquely able to generate aging, pH sensitivity[109,156], electromagnetic, photoluminescence158159160161, and quantum mechanical effects162163164165. o These types of phenomena overlap a number of the seemingly unrelated basic science findings previously reported for HMs[30,32,33,50,98]. Even the variations in modern nanotechnology using mechanical manufacturing processes from ball milling and vortexing or sonication to water jet treatment of liquids are empirically shown to generate nanoparticles from larger bulk forms in a top-down manner[20,25,116,166]. "
Available from: Peng GU
- "The possibility of fabricating a SPASER (surface plasmon amplification by stimulated emission of radiation) source has attracted considerable attentions during the last ten years, because of its potential applications from sensing and biomedicine to imaging and information technology      . "
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ABSTRACT: We present the synthesis and photophysical study of a new type of fluorescent gold core–polystyrene shell nanoparticles fabricated by emulsion polymerization at neutral pH. The thickness of the PS shell can be controlled by varying the synthesis conditions. Decrease in the fluorescence intensity and lifetime of Rhodamine 800 (Rh800) were observed, indicating energy transfer from Rh800 to gold nanorods. This study suggests the possibility of exploiting dye-doped polystyrene shells as a gain medium to compensate for the energy loss of longitudinal surface plasmon resonance of gold nanorods and paving the way for eventually realizing a SPASER (surface plasmon amplification by stimulated emission of radiation) optical source of tuneable wavelength.
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ABSTRACT: Localized surface plasmon singularities from metal nanoparticles in active media are investigated on the basis of classic linear electrodynamics. It is found that the gain threshold is inversely proportional to the shape factor of the particle. When relating this phenomenon to the plasmonic field-enhanced emission from gain units, we show that the maximum electric field around spheroidal particles impacts upon the gain threshold via a two-exponential decay function. Our results provide a way to reduce the gain requirement in metal nanoparticle-based spaser or random laser systems.
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