Negative refraction of light in an atomic medium

TL;DR

This paper demonstrates negative refraction of light in an atomic medium using exact simulations, showing potential for applications like superlensing without artificial metamaterials.

Contribution

It introduces a method to achieve negative refraction in atomic arrays, providing an intuitive band-based explanation and showing robustness and enhancement possibilities.

Findings

High transmission negative refraction achieved in atomic arrays

Negative refraction is robust to lattice imperfections

Refraction can be enhanced via subradiance

Abstract

The quest to manipulate light propagation in ways not possible with natural media has driven the development of artificially structured metamaterials. One of the most striking effects is negative refraction, where the light beam deflects away from the boundary normal. However, due to material characteristics, the applications of this phenomenon, such as lensing that surpasses the diffraction limit, have been constrained. Here, we demonstrate negative refraction of light in an atomic medium without the use of artificial metamaterials, employing essentially exact simulations of light propagation. High transmission negative refraction is achieved in atomic arrays for different level structures and lattice constants, within the scope of currently realised experimental systems. We introduce an intuitive description of negative refraction based on collective excitation bands, whose transverse group velocities are antiparallel to the excitation quasi-momenta. We also illustrate how this phenomenon is robust to lattice imperfections and can be significantly enhanced through subradiance.