Robust waveguide against surface perturbations due to band inversion in two kinds of single-negative metamaterials

We experimentally study the guided wave along the interface between e -negative (ENG) material and μ -negative (MNG) material when the interface is distorted. It is demonstrated that the guided mode is robust against various interface perturbations, owing to the band inversion between ENG and MNG materials. For comparison, the guided modes in double-positive material sandwiched by two MNG materials are also investigated under the same interface perturbations. Without band inversion, the guided modes in the sandwich waveguide are strongly affected by the interface distortions. Numerical simulations agree well with the experimental results.