Chiral Epsilon-Near-Zero Metamaterials

In a paper published in Physical Review Letters we demonstrate that a one-dimensional stack of achiral material can exhibit electromagnetic chirality…

Artificial chirality is currently a very much-researched field both from a fundamental point of view and for its applications in molecular biology, life science, optics, crystallography and particle physics.

In this context, plasmonic-based metamaterials are the natural platform of choice because their smallest constituents (meta-atoms) can be engineered to exhibit artificial chirality. This is usually achieved by breaking the spatial symmetry of the meta-atoms, structuring plasmonic materials at the nanoscale, either in 3D (akin to natural chirality) or in 2D, but never in 1D.

Here we unveil the optical properties of a new class of artificial chiral metamaterials, whose purely achiral constituents are structured in one dimension only. By using a multiscale technique we show that multilayers engineered at a fraction of the operating wavelength can exhibit a non-vanishing chiral tensor, even when 2D or 3D chiral asymmetries are not present. Most remarkably, the effect of the chiral response can be dramatically enhanced when the effective medium is designed to have vanishing effective permittivity.

Chiral Epsilon-Near-Zero Metamaterials

The transmission amplitudes of right-handed and left-handed circular polarized plane waves are not equal for light incident at an angle, as manifestation of 1D chirality.

  1. Rizza, A. Di Falco, M. Scalora, A. Ciattoni, “One-Dimensional Chirality: Strong Optical Activity in Epsilon-Near-Zero Metamaterials”, Phys. Rev. Lett. 115, 057401 (2015).

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