Low- and high-intensity velocity selective coherent population trapping in a two-level systemD. Wilkowski1, M. Chalony1, R. Kaiser1 and A. Kastberg2
1 Institut Non Linéaire de Nice, CNRS, UMR 6618, University de Nice Sophia-Antipolis - F-06560 Valbonne, France, EU
2 Umeå University, Department of Physics - SE-90187 Umeå, Sweden, EU
received 24 December 2008; accepted in final form 14 May 2009; published June 2009
published online 17 June 2009
An experimental investigation is made of sub-recoil cooling by velocity selective coherent population trapping in a two-level system in Sr. The experiment is carried out using the narrow linewidth intercombination line at 689 nm. Here, the ratio between the recoil shift and the linewidth is as high as 0.64. We show that, on top of a broader momentum profile, subrecoil features develop, whose amplitude is strongly dependent on the detuning from resonance. We attribute this structure to a velocity selective coherent population trapping mechanism. We also show that the population trapping phenomenon leads to complex momentum profiles in the case of highly saturated transitions, displaying a multitude of subrecoil features at integer multiples of the recoil momentum.
37.10.De - Atom cooling methods.
37.10.Vz - Mechanical effects of light on atoms, molecules, and ions.
42.50.Gy - Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption.
© EPLA 2009