Anomalous Electromagnetic Response of Composite Nanoparticle

Abstract

We have analysed the anomalous electromagnetic response of composite nanoparticle  formed by two conjoined half cylinders of arbitrary complex permittivity and radius.  This geometry has been proposed in the special configuration to from a resonant  optical nano circuit and attempts to analytically solved its scattering properties using  mode matching analysis, integral transformation and coordinate mapping have led to  non physical solutions and strong numerical instabilities. We have shown that these  challenges are associated with counterintuitive resonant phenomena which leaded to  continuous frequency range over which distributed Plasmon resonances may support  unbounded values of absorption or gain efficiency i.e. finite absorption or grain even  in the limit of infinitesimally small material loss/gain. We solved the complete  scattering problem associated with this geometry derived closed form expressions for  the induced fields inside and outside this composite particle. This solution provides  valuable physical insights into the complex wave interaction of this particle over a  broad range of frequencies which provide exciting possibilities for energy  concentration, harvesting and spasars. This absorption paradox has been shown to be  associated with the singularities in the geometry and the adiabatic focusing of broad  band surface plasmons supported at the corners. A close form solution was derived  for the scattering and absorption properties of the composite nanostructure and  simple conditions on the material permittivity have been derived to control the  position of the absorption band.