https://doi.org/10.1140/epjd/e2004-00123-2
Fluorescence from doubly driven four-level atoms
A density matrix approach
Raman Research Institute, Sadashivnagar, Bangalore 560 080, India
Corresponding author: a andal@rri.res.in
Received:
14
May
2004
Revised:
2
July
2004
Published online:
21
September
2004
The unusually narrow features in the fluorescence from 85Rb driven by two laser fields L1 and L2, reported in [1], are explained on the basis of a four-level density matrix calculation. The L2 laser enables atom transfer to the fluorescing levels connected by the strong L1 laser. In turn the L1 laser causes the Autler-Townes splitting of the upper levels connected by L2 laser. These two effects are shown to maximise fluorescence within a narrow spectral range of the scanned L2 laser due to velocity selection of atoms from co-propagating and counter propagating L1 and L2 lasers. The analysis reveals the existence of narrow spectral features from a collection of atoms at room temperature even in the absence of induced coherences between the levels.
PACS: 42.50.Hz – Strong-field excitation of optical transitions in quantum systems; multiphoton processes; dynamic Stark shift / 32.80.Bx – Level crossing and optical pumping
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2004
