Cancellation of the coherent accumulation in rubidium atoms excited by a train of femtosecond pulses
We investigated the coherence accumulation in Rb atoms excited by a train of femtosecond pulses. The coherence accumulation results in the velocity selective optical pumping of Rb hyperfine levels, observed by a cw probe laser. The effects of the pulse train excitation on the cw probe laser transmission were investigated, depending on the probe laser power. We observed the probe laser absorption increase in the strong probe case, followed by the reduction of the modulations in the probe laser absorption. Results show that accumulation of population and coherence can be effectively reduced and eventually destroyed by increasing the cw laser intensity. A strong cw laser can therefore serve as a switch from the pulse-train to pulse-by-pulse type of interaction of Rb atoms with the fs laser. We developed a density-matrix based theoretical model of the eight-level Rb atoms interacting with the fs and cw laser fields, and present agreement with the experimental results.
Physical Review A
- Pub Date:
- October 2007
- Coherent control of atomic interactions with photons;
- Effects of atomic coherence on propagation absorption and amplification of light;
- electromagnetically induced transparency and absorption