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Conference on Lasers and Electro-Optics

Polarization dependence of optical suppression in sodium

W. DeGraffenreid, Charles Y. H. Tsao, Y. Wang, J. Weiner, Reginaldo de Jesus Napolitano

Published Nov 27, 2002• 0 citations
Publisher

Abstract

Summary form only given. The use of a cold beam of sodium allows us to probe the angular dependence of the linear polarization case. We have measured the decrease in the ionizing collision rate by monitoring the fractional decrease in photoassociative ionisation (PAI) in a Zeeman-slowed sodium beam. We see that the suppression with light polarized perpendicular to the atomic beam is greater than that with parallel. Increased suppression is observed with increasing intensity of the light.

DOI
10.1109/iqec.1998.680418

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Summary form only given. The use of a cold beam of sodium allows us to probe the angular dependence of the linear polarization case. We have measured the decrease in the ionizing collision rate by monitoring the fractional decrease in photoassociative ionisation (PAI) in a Zeeman-slowed sodium beam. We see that the suppression with light polarized perpendicular to the atomic beam is greater than that with parallel. Increased suppression is observed with increasing intensity of the light.
\n We report the observation of polarization anisotropy in the optical\nsuppression of photoassociative ionization (PAI) collisions. Binary\ncollisions occur within a tightly collimated and optically cooled velocity\ngroup of a single sodium beam. A laser beam, blue-detuned with respect to\nthe atomic resonance transition, crosses the atomic beam and suppresses the\nPAI rate. We measure this suppression as a function of intensity and\nelectric field vector aligned parallel or perpendicular to the atomic beam\naxis. Quantum close-coupling and multichannel curve-crossing calculations of\nmodel systems yield insight into the nature of the anisotropy and are in\nreasonable agreement with the measurements.\n\n \n
Three-dimensional quantum scattering calculations predict that the degree of optical shielding of cold collisions saturates with increasing intensity very differently from two-state models and is sensitive to the polarization of the shielding light. We report measurements showing how suppression of Na photoassociative ionization (PAI) rates is sensitive to the intensity and polarization of the shielding laser. At higher intensities, circular polarization suppresses PAI rates an order of magnitude more effectively than linear polarization, in qualitative agreement with our model calculations.
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