International Workshop on Atomic Interactions in Laser Fields - Abstracts
S.N. Atutov1,3, V.Biancalana2, R.Calabrese1, V.Guidi1, P.Lenisa1, E.Mariotti2, L.Moi2, K.Nasirov2,3, S.P.Pod'yachev2,3
1Dipartimento di Fisica Universita'
di Ferrara - INFN Sez. Ferrara - Italy
2Dipartimento di Fisica Universita' di Siena - INFM
UdR Siena - Italy
3permanent address: Institute of Automation and
Electrometry - Novosibirsk Russia
Laser cooling and trapping of atoms and ions are routinely made by using single-mode laser radiation. Laser chirping or Zeeman tuning are the methods used to circumvent the Doppler shift of the atomic absorption line. We show that in some circumstances laser cooling performed with "white" light is more effective than the one made with monochromatic radiation. This is verified when very large collection efficiency in trapping or large velocity capture range are needed while preserving a high cooling rate.
In order to get such results, the broad-band laser radiation should show a sharp edge in the frequency domain and a frequency separation between the different frequencies comparable with the homogeneous linewidth. The first condition guarantees the lowest temperature, while the second one simulates the "white-light" condition. We generate such a spectrum by using an acousto-optic modulator coupled to a passive double ring cavity. The special coupling between this cavity and the pump laser allows us to get very high efficiency, optimal stability and a total control of the laser spectrum shape.
We have already obtained very good results by making laser cooling of fast Li ions confined in a storage ring. In a direct comparison with single-mode laser cooling, we show that white-light cooling is much more efficient to counteract strong intrabeam heating and leads to lower longitudinal beam temperatures at higher ion densities.
White-light cooling can be very effective also when the collection efficiency of atoms in a magneto optical trap has to be maximized. As it is known the collection efficiency increases very fast with the velocity capture range that is directly related to the laser linewidth. We present a theoretical analysis and some preliminary results obtained in a Sodium MOT.