There is provided a structure for supporting propagation of surface plasmon polaritons. The structure includes a plasmonic material region and a dielectric material region, disposed adjacent to a selected surface of the plasmonic material region. At least one of the plasmonic material region and the dielectric material region have a dielectric permittivity distribution that is specified as a function of depth through the corresponding material region. This dielectric permittivity distribution is selected to impose prespecified group velocities, v.sub.gj, on a dispersion relation for a surface polaritonic mode of the structure for at least one of a corresponding set of prespecified frequencies, .omega..sub.j, and corresponding set of prespecified wavevectors, where j=1 to N.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
This invention was made with Government support under Grant No. DMR0819762 awarded by the National Science Foundation, Grant No. DE-FG02-99ER45778 awarded by the Department of Energy, and Grant No. W911NF-07-D-0004 awarded by the Army. The Government has certain rights in the invention.