Recent theoretical and experimental works demonstrate that effective surface plasmon polaritons (ESPPs) induced by structural dispersion in bounded waveguide are perfect lowfrequency.counterparts of optical SPPs both for the double-layered and multi-layered systems. In all these efforts, the lateral dimension of each layer was assumed to be the same and the dispersion of the ESPPs was only tuned by the dielectric permittivity in each layer. Inevitably, the dielectric loss will deteriorate the tr
