Negative refraction with tunable absorption in an active dense gas of atoms

TL;DR

This paper demonstrates how to achieve tunable, near-lossless negative refraction in a dense atomic gas by using quantum interference and gain mechanisms, with potential applications in advanced optical devices.

Contribution

It introduces a method to actively control absorption in dense atomic gases to realize negative index materials with negligible losses, combining quantum interference and gain.

Findings

Gain mechanisms can effectively cancel absorption in dense gases.

Metastable Neon is a promising candidate for experimental realization.

Nonlinear optical Bloch equations model the optical response accurately.

Abstract

Applications of negative index materials (NIM) presently are severely limited by absorption. Next to improvements of metamaterial designs, it has been suggested that dense gases of atoms could form a NIM with negligible losses. In such gases, the low absorption is facilitated by quantum interference. Here, we show that additional gain mechanisms can be used to tune and effectively remove absorption in a dense gas NIM. In our setup, the atoms are coherently prepared by control laser fields, and further driven by a weak incoherent pump field to induce gain. We employ nonlinear optical Bloch equations to analyze the optical response. Metastable Neon is identified as a suitable experimental candidate at infrared frequencies to implement a lossless active negative index material.