Theory of Supercoupling, Squeezing Wave Energy, and Field Confinement in Narrow Channels and Tight Bends Using Epsilon-Near-Zero Metamaterials

TL;DR

This paper develops a comprehensive theory of supercoupling and field confinement in narrow channels using epsilon-near-zero metamaterials, revealing new physical insights, applications, and effects of material losses.

Contribution

It introduces detailed physical insights, explores new applications, and systematically studies wave propagation in epsilon-near-zero materials within narrow waveguides and cavities.

Findings

Epsilon-near-zero materials enable near-perfect tunneling through narrow channels.

Reflectivity can be independent of geometry in certain epsilon-near-zero configurations.

Metamaterial implementations include metallic waveguides, microstrip lines, and wire media.

Abstract

In this work, we investigate the detailed theory of the supercoupling, anomalous tunneling effect, and field confinement originally identified in [M. Silveirinha, N. Engheta, Phys. Rev. Lett. 97, 157403, (2006)], where we demonstrated the possibility of using materials with permittivity near zero to drastically improve the transmission of electromagnetic energy through a narrow irregular channel with very subwavelength transverse cross-section. Here, we present additional physical insights, describe new applications of the tunneling effect in relevant waveguide scenarios (e.g., the "perfect" or "super" waveguide coupling), study the effect of metal losses in the metallic walls, and the possibility of using epsilon-near zero materials to confine energy in a subwavelength cavity with gigantic field enhancement. In addition, we systematically study the propagation of electromagnetic waves through narrow channels filled with anisotropic epsilon-near zero materials. It is demonstrated that these materials may have interesting potentials, and that for some particular geometries the reflectivity of the channel is independent of the specific dimensions or parameters of epsilon-near zero transition. We also describe several realistic metamaterial implementations of the studied problems, based on standard metallic waveguides, microstrip line configurations, and wire media.