Linear transformation optics for plasmonics

The method of transformation optics (TO) has recently been applied to the problem of manipulating the flow of surface plasmon polaritons (SPPs) along metal-dielectric interfaces. Although it allows one to theoretically control the flow in any manner desired, it usually leads to material properties not found in nature, thus making the realization of theoretical potentialities impractical. Therefore, artificial materials (called metamaterials), with both inhomogeneous and anisotropic electromagnetic response, are normally required to create the optical space designed with the TO method. In this paper, by utilizing linear coordinate transformations, we demonstrate that it is possible to maneuver the flow of SPPs in various ways within the realm of homogeneous metamaterials. Specifically, we describe how to construct a plasmon guider for a particular nonflat surface, an invisibility cloak that renders objects undetectable via SPPs, and a concentrator of the SPPs' energy. The functionalities of these devices are visualized, and their performance is investigated, using finite-element simulations. The results presented show that the method of linear transformations is a simple, viable, and effective approach to the design of feasible plasmonic devices based on homogenous materials. (c) 2012 Optical Society of America