Off-resonance absorption and dispersion in a Doppler-broadened medium

TL;DR

This paper investigates how Doppler broadening affects absorption and dispersion in atomic media, providing simplified models that match experimental data and highlight the dominance of dispersion away from resonance.

Contribution

It introduces and validates simplified susceptibility models for Doppler-broadened media, enhancing understanding of atom-light interactions far from resonance.

Findings

Dispersion dominates absorption far from resonance.

Simplified models accurately match experimental data.

Approximate susceptibility functions facilitate analysis.

Abstract

We study the absorptive and dispersive properties of Doppler-broadened atomic media as a function of detuning. Beginning from the exact lineshape calculated for a two-level atom, a series of approximations to the electric susceptibility are made. These simplified functions facilitate direct comparison between absorption and dispersion, and show that dispersion dominates the atom-light interaction far from resonance. The calculated absorption and dispersion are compared to experimental data, showing the validity of the approximations.