Nonlinear effects in optical pumping of a cold and slow atomic beam

Year: 2015

Authors: Porfido N., Bezuglov N.N., Bruvelis M., Shayeganrad G., Birindelli S., Tantussi F., Guerri I., Viteau M., Fioretti A., Ciampini D., Allegrini M., Comparat D., Arimondo E., Ekers A., Fuso F.

Autors Affiliation: Univ Pisa, Dipartimento Fis Enrico Fermi, I-56127 Pisa, Italy; St Petersburg State Univ, Fac Phys, St Petersburg 198904, Russia; Univ ITMO, Dept Phys, St Petersburg 197101, Russia; Univ Latvia, Inst Atom Phys & Spect, LV-1586 Riga, Latvia; TESCAN Orsay, Orsay Phys, F-13710 Fuveau, France; CNR, INO, I-56124 Pisa, Italy; Consorzio Nazl Interuniv Sci Fis Mat, CNISM, Sez Pisa, I-56127 Pisa, Italy; Univ Paris 11, CNRS, Aime Cotton Lab, ENS Cachan, F-91405 Orsay, France; King Abdullah Univ Sci & Technol, Comp Elect & Math Sci & Engn Div, Thuwal 239556900, Saudi Arabia.

Abstract: By photoionizing hyperfine (HF) levels of the Cs state 6 P-2(3/2) in a slow and cold atom beam, we find how their population depends on the excitation laser power. The long time (around 180 mu s) spent by the slow atoms inside the resonant laser beam is large enough to enable exploration of a unique atom-light interaction regime heavily affected by time-dependent optical pumping. We demonstrate that, under such conditions, the onset of nonlinear effects in the population dynamics and optical pumping occurs at excitation laser intensities much smaller than the conventional respective saturation values. The evolution of population within the HF structure is calculated by numerical integration of the multilevel optical Bloch equations. The agreement between numerical results and experiment outcomes is excellent. All main features in the experimental findings are explained by the occurrence of dark and bright resonances leading to power-dependent branching coefficients.

Journal/Review: PHYSICAL REVIEW A

Volume: 92 (4)      Pages from: 43408-1  to: 43408-11

More Information: N.P., G.S., A.F., I.G., D.C., M.V., and F.F. acknowledge gratefully the support of the European Commission Seventh Framework Programme under Grant No. 251391 MC-IAPP COLDBEAMS. This collaborative work was supported also by the European Commission Seventh Framework Programme IRSES project COLIMA and the Centre of Excellence FOTONIKA-LV (European Commission Seventh Framework Programme project REGPOT-CT-2011-285912-FOTONIKA). N.B. acknowledges the support from Government of the Russian Federation Grant No. 074-U01, and M.B. and A.E. acknowledge the support from U.S. Office of Naval Research Grant No. N00014-12-1-0514. We thank Professor M. Auzinsh for helpful discussions on the bright-resonance phenomena and N. Puccini and E. Andreoni for their assistance with the experiment.
KeyWords: Saturation Spectroscopy; Multilevel Atoms; Cesium; Laser; Absorption; Photoionization; Intensity; Systems; State; Trap
DOI: 10.1103/PhysRevA.92.043408

Citations: 13
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