Transmission and beam shaping of a Gaussian light beam passing through a dense Rubidium vapour

Abstract

Laser light can exhibit nonlinear behaviour when interacting with dense atomic vapours. This can give rise to a variety of interesting phenomena such as slow light and optically induced transparency. Recently A.~J. van Lange measured nonlinear transmission of light through a Rubidium vapour and developed a physical model to describe these measurements. Van Lange also investigated the formation of different beam profiles, in a dense Rubidium vapour and from Gaussian input beams, as a function of intensity and optical frequency.

Here we expand on van Lange's measurements by measuring over a large frequency range which includes multiple atomic transition lines and by employing off-axis holography which allows for simultaneous measurement of the intensity and phase. Analysis of beam profiles based on the structural similarity index (SSIM) uncovered beam profiles whose path through intensity-detuning space could be described with van Lange's generalised detuning curve. Off-axis holography measurements are in agreement with regular intensity measurements but exhibits a greater amount of noise.