Anomalous Electromagnetic Response of Composite Nanoparticle

Abstract

We have analysed the anomalous electromagnetic response of composite nanoparticleformed by two conjoined half cylinders of arbitrary complex permittivity and radius.This geometry has been proposed in the special configuration to from a resonantoptical nano circuit and attempts to analytically solved its scattering properties usingmode matching analysis, integral transformation and coordinate mapping have led tonon physical solutions and strong numerical instabilities. We have shown that thesechallenges are associated with counterintuitive resonant phenomena which leaded tocontinuous frequency range over which distributed Plasmon resonances may supportunbounded values of absorption or gain efficiency i.e. finite absorption or grain evenin the limit of infinitesimally small material loss/gain. We solved the completescattering problem associated with this geometry derived closed form expressions forthe induced fields inside and outside this composite particle. This solution providesvaluable physical insights into the complex wave interaction of this particle over abroad range of frequencies which provide exciting possibilities for energyconcentration, harvesting and spasars. This absorption paradox has been shown to beassociated with the singularities in the geometry and the adiabatic focusing of broadband surface plasmons supported at the corners. A close form solution was derivedfor the scattering and absorption properties of the composite nanostructure andsimple conditions on the material permittivity have been derived to control theposition of the absorption band