Optical pattern formation with a 2-level nonlinearity

TL;DR

This paper explores how optical patterns spontaneously form and disappear in a laser beam passing through cold Rubidium atoms, highlighting the unique effects of 2-level atomic nonlinearity on pattern dynamics.

Contribution

It provides the first combined experimental and theoretical analysis of pattern formation specifically in a 2-level atomic system, demonstrating saturation effects.

Findings

Patterns form at certain intensities and vanish at high intensities due to saturation.

Experimental observations align with theoretical predictions.

The study advances understanding of nonlinear optical phenomena in atomic systems.

Abstract

We present an experimental and theoretical investigation of spontaneous pattern formation in the transverse section of a single retro-reflected laser beam passing through a cloud of cold Rubidium atoms. In contrast to previously investigated systems, the nonlinearity at work here is that of a 2-level atom, which realizes the paradigmatic situation considered in many theoretical studies of optical pattern formation. In particular, we are able to observe the disappearance of the patterns at high intensity due to the intrinsic saturable character of 2-level atomic transitions.