Slow-light enhanced light-matter interactions with applications to gas sensing

TL;DR

This paper demonstrates that slow-light effects in Bragg stacks can significantly enhance gas absorption signals, enabling miniaturized optical gas sensors with much shorter optical paths.

Contribution

It extends perturbation theory to dispersive gases in Bragg stacks, showing substantial signal enhancement for gas detection in microsystems.

Findings

Signal enhancement factor of at least 100 in Bragg stacks

Reduction of optical path length to 1 mm for visible to near-infrared detection

Potential for miniaturized optical gas sensors

Abstract

Optical gas detection in microsystems is limited by the short micron scale optical path length available. Recently, the concept of slow-light enhanced absorption has been proposed as a route to compensate for the short path length in miniaturized absorption cells. We extend the previous perturbation theory to the case of a Bragg stack infiltrated by a spectrally strongly dispersive gas with a narrow and distinct absorption peak. We show that considerable signal enhancement is possible. As an example, we consider a Bragg stack consisting of PMMA infiltrated by O2. Here, the required optical path length for visible to near-infrared detection (~760 nm) can be reduced by at least a factor of 10^2, making a path length of 1 mm feasible. By using this technique, optical gas detection can potentially be made possible in microsystems.