Devices and methods are provided for controlling the propagation of electromagnetic radiation on conductive surfaces via the presence of coupled subwavelength conductor-dielectric unit plasmonic resonators. In some embodiments, the dimensions of the unit plasmonic resonators are selected to produce modal overlap and coupling between surface plasmons of adjacent conductive surfaces. The properties of the unit plasmonic resonators may be spatially graded to produce the slowing down and/or trapping of electromagnetic waves. Methods are provided for calculating resonant modes of structures that involve intra-resonator plasmonic coupling. Various example implementations of such devices and structures are provided.
