Absorption imaging of a quasi 2D gas: a multiple scattering analysis

TL;DR

This paper analyzes how multiple scattering affects absorption imaging of quasi-2D ultracold gases, revealing deviations from classical laws and providing insights for accurate in situ diagnostics.

Contribution

It introduces a Monte Carlo simulation approach to study multiple scattering effects in 2D gases, highlighting differences from 3D absorption models.

Findings

Absorption cross-section is significantly modified by multiple scattering.

Optical density varies with detuning and gas thickness.

Deviations from Beer-Lambert law are outlined for 2D gases.

Abstract

Absorption imaging with quasi-resonant laser light is a commonly used technique to probe ultra-cold atomic gases in various geometries. Here we investigate some non-trivial aspects of this method when it is applied to in situ diagnosis of a quasi two-dimensional gas. Using Monte Carlo simulations we study the modification of the absorption cross-section of a photon when it undergoes multiple scattering in the gas. We determine the variations of the optical density with various parameters, such as the detuning of the light from the atomic resonance and the thickness of the gas. We compare our results to the known three-dimensional result (Beer-Lambert law) and outline the specific features of the two-dimensional case.