Optical Magnetism in Planar Metamaterial Heterostructures

TL;DR

This paper demonstrates that planar, one-dimensional metal/dielectric multilayer metamaterials can exhibit artificial magnetism and hyperbolic dispersion for both TE and TM polarizations, simplifying design and expanding potential applications.

Contribution

It introduces and experimentally verifies a mechanism for magnetic hyperbolic dispersion in 1D planar metamaterials for both TE and TM polarizations, broadening the scope of optical magnetism.

Findings

Magnetic response in hyperbolic metamaterials is anisotropic.

TE interface-bound states are supported, similar to TM surface plasmons.

Simplifies the design of artificial magnetism in lithography-free systems.

Abstract

Harnessing artificial optical magnetism requires rather complex two- and three-dimensional structures, examples include split-ring and fishnet metamaterials and nanoparticles with non-trivial magnetic properties. By contrast, dielectric properties can be tailored even in planar and pattern-free, one-dimensional (1D) arrangements, for example metal/dielectric multilayer metamaterials. These systems are extensively investigated due to their hyperbolic and plasmonic response, which, however, is considered to be limited to TM polarization, based on the general consensus that they do not possess interesting magnetic properties. In this work, we tackle these two seemingly unrelated issues simultaneously, by proposing conceptually and demonstrating experimentally a mechanism for artificial magnetism in planar, 1D metamaterials. We show experimentally that the magnetic response of metal/high-index dielectric hyperbolic metamaterials can be anisotropic, leading to frequency regimes of magnetic hyperbolic dispersion. We investigate the implications of our results for TE polarization and show that such systems can support TE interface-bound states, analogous to their TM counterparts, surface plasmon polaritons. Our results simplify the structural complexity for tailoring artificial magnetism in lithography-free systems and generalize the concept of plasmonic and hyperbolic properties to encompass both TE and TM polarizations at optical frequencies.