Quadraxial metamaterial

TL;DR

This paper investigates the electromagnetic wave dispersion in a specialized metamaterial with a Lorentz-like permittivity tensor, revealing unique optical axes and wave propagation behaviors, including conical refraction effects.

Contribution

It introduces a detailed analysis of a triple wire medium metamaterial with four optic axes and explores wave propagation and refraction phenomena across frequencies.

Findings

Metamaterial has four frequency-independent optic axes.

Supports two propagating waves in most directions, except along axes.

Exhibits conical refraction and supports five waves above plasma frequency.

Abstract

We study the dispersion of electromagnetic waves in a spatially dispersive metamaterial with Lorentz-like dependence of principal permittivity tensor components on the respective components of the wave vector performing the analysis of isofrequency contours. The considered permittivity tensor describes triple non-connected wire medium. It is demonstrated that the metamaterial has four optic axes in the frequency range below artificial plasma frequency. The directions of the optical axes do not depend on frequency and coincide with the diagonals of quadrants. The metamaterial supports two propagating electromagnetic waves in all directions of space except the directions of axes. The conical refraction effect is observed for all four optic axes both below and above artificial plasma frequency where the metamaterial supports five propagating waves in most of the directions.