Ultracompact Surface Plasmon Polariton Beam Focusing with Metal-Coated Nanoshell Structures

In this paper, we report on beam focusing and on directing of surface plasmon polaritons (SPPs) with metal-coated nanoshell chain structures. Using nanoshells enhances the interaction between particles and leads to much higher field intensities in the focal point. Beam focusing has been realized over a wide wavelength range, due to the inherent large tuneablity of the plasmon resonance in the underlying nanoshells. The focusing device topologies proposed here are easy to adapt to long wavelength operations. Finally, a simplified metallic strip structure was proposed to explain the broadband characteristics of the chain structures as well as to compare and to verify its proper design.