Nonlinear lensing mechanisms in a cloud of cold atoms

Labeyrie, G. and Gattobigio, G. L. and Chaneliere, T. and Lippi, G. L. and Ackemann, T. and Kaiser, R. (2007) Nonlinear lensing mechanisms in a cloud of cold atoms. European Physical Journal D: Atomic, Molecular, Optical and Plasma Physics, 41 (2). pp. 337-348. ISSN 1434-6060 (https://doi.org/10.1140/epjd/e2006-00234-8)

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Abstract

We present an experimental study of nonlinear lensing of near-resonant light by a cloud of laser-cooled rubidium atoms, specifically aimed at understanding the role of the interaction time between the light and the atomic vapor. We identify four different nonlinear mechanisms, each associated with a different time constant: electronic nonlinearity, Zeeman optical pumping, hyperfine optical pumping and radiation pressure. Our observations can be quite accurately reproduced using a simple rate equation model which allows for a straightforward discussion of the various effects. The results are important for planning more refined experiments on transverse nonlinear optics and self-organization in samples of cold atoms.