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Due to their many potential applications, there is an increasing interest in studying hybrid systems composed of optically active media and plasmonic metamaterials. In this work we focus on a particular system which consists of an optically active silica core covered by a gold shell. We find that the spaser (surface plasmon amplification by stimulated emission of radiation) conditions can be found at the poles of the scattering cross section of the system, a result that remains valid beyond the geometry studied. We explored a wide range of parameters that cover most of the usual experimental conditions in terms of the geometry of the system and the wavelength of excitation. We show that the conditions of spaser generation necessarily require full loss compensation, but the opposite is not necessarily true. Our results, which are independent of the detailed response of the active medium, provide the gain needed and the wavelength of the spasers that can be produced by a particular geometry, discussing also the possibility of turning the system into optical amplifiers and SERS (surface enhanced Raman spectroscopy) substrates with huge enhancements. We believe that our results can find numerous applications. In particular, they can be useful for experimentalists studying similar systems in both, tuning the experimental conditions and interpreting the results.
We propose a new approach to understand the time-dependent temperature increasing process of gold-silica core-shell nanoparticles injected into chicken tissues under near-infrared laser irradiation. Gold nanoshells strongly absorb near-infrared radia
We theoretically introduce a topological spaser, which consists of a hexagonal array of plasmonic metal nanoshells containing an achiral gain medium in their cores. Such a spaser can generate two mutually time-reversed chiral surface plasmon modes in
We study the effect of off-resonant plasmon modes on spaser threshold in nanoparticle-based spasers. We develop an analytical semiclassical model and derive spaser threshold condition accounting for gain coupling to higher-order plasmons. We show tha
Magnetic nanoparticles (NP) of magnetite (Fe3O4) coated with oleic acid (OA) and dodecanoic acid (DA) were synthesized and investigated through Transmission Electron Microscopy (TEM),magnetization M, and ac magnetic susceptibility measurements. The O
A novel approach to control the grain size of oxide thin film materials has been investigated. Perovskite BaTiO3 shows interesting grain structures when deposited on gold predeposited, (111)-oriented, singlecrystal SrTiO3 substrates. Solid oxide film