Excitation of sodium atoms by 330-nm laser pulses

Igor M. Beterov, I. I. Ryabtsev, Efim V. Pestryakov +4 more

Ursula Domiaty, Dieter Gruber, Laurentius Windholz +5 more

Arthur L. Robinson

Gautier Vilmart, Michael S. Scherman, Anais Chiabaut +1 more

levels of atomic sodium using ultrashort laser pulses in a stepwise excitation scheme. Two broadband femtosecond laser pulses are used to excite the 6S level from the 3S ground level in sodium vapor. The first one is simultaneously resonant with the D1 and D2 lines of the 3S→3P transition, and the second one with the 3P→6S transition. The delay between the two pulses is scanned in order to probe the dephasing between the two excited intermediate levels. Quantum beating is observed by monitoring the fluorescence signals at 330 nm and 515 nm, namely transition 4P→3S and 6S→3P, respectively. Signals are compared to a semi-classical model that reproduces the oscillations with a very good agreement.

E. Krüger

The steady-state absorption of a beam of sodium atoms irradiated by a train of pulses from a mode-locked dye laser has been measured. The sodium atoms were prepared as two-level systems by optical pumping with a two-mode laser. Absorption spectra on the 589.0-nm D2 line were recorded over 20 GHz with a frequency-stabilized, tunable, mode-locked dye laser having a bandwidth of 3.7 GHz and a mode spacing of 82 MHz. The laser-pulse profile was determined from the spectral profile assuming transform-limited pulses and was incorporated in theoretical calculations of excitation spectra obtained by numerical integration of the optical Bloch equations. By comparison of measured absorption spectra and theoretical excitation spectra the validity of the weak-field solution as well as the predicted saturation behavior were fully verified by the experimental results. For the highest level of irradiation applied, the laser pulses were identified as π pulses.

V. I. Balykin, Vladilen S Letokhov, V.I. Mishin