Electromagnetic transmission enhancement in subwavelength inhomogeneous plasmas modulated by negative-permeability metamaterials

Abstract Pairing overdense or epsilon-negative plasmas with mu-negative (MNG) metamaterials has been demonstrated to be an effective way to enhance electromagnetic transmission efficiency in plasmas. However, existing theoretical and simulative works mainly consider ideal homogeneous models. In this paper, we further explored the influence of inhomogeneity on the matching processes between MNG metamaterials and 1D/2D inhomogeneous plasmas in the subwavelength regime. It is shown that for 1D subwavelength inhomogeneous plasmas, there is only one parameter matching region for MNG metamaterials, where the optimal constitutive parameters depend on the relative/absolute thickness of MNG metamaterials and plasma, incident angle and specific density profiles of plasma, especially the position of maximum plasma frequency. For 2D subwavelength inhomogeneous plasmas, since MNG metamaterials can locally match with plasma at different positions and the trajectory of electromagnetic waves can be further modulated by the density gradients perpendicular to the incident direction, multiple or single transmission peaks can be observed under symmetric or asymmetric density profiles, respectively.