Structural dispersion-based reduction of loss in epsilon-near-zero and surface plasmon polariton waves.

The field of plasmonics has substantially affected the study of light-matter interactions at the subwavelength scale. However, dissipation losses still remain an inevitable obstacle in the development of plasmonic-based wave propagation. Although different materials with moderate losses are being extensively studied, absorption arguably continues to be the key challenge in the field. Here, we theoretically and numerically investigate a different route toward the reduction of loss in propagating plasmon waves. Rather than focusing on a material-based approach, we take advantage of structural dispersion in waveguides to manipulate effective material parameters, thus leading to smaller losses. The potential of this approach is illustrated with two examples: plane-wave propagation within a bulk epsilon-near-zero medium and surface plasmon polariton propagation at the interface of a medium with negative permittivity. We provide the recipe for a practical implementation at mid-infrared frequencies. Our results might represent an important step toward the development of low-loss plasmonic technologies.