Darmstadt 2008 – scientific programme
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A: Fachverband Atomphysik
A 13: Posters: Photoionization and atomic systems in external fields
A 13.3: Poster
Tuesday, March 11, 2008, 16:30–18:30, Poster C3
Enhanced Four-Wave Mixing in mercury isotopes, prepared by Stark-chirped rapid adiabatic passage — •martin oberst, jens klein, and thomas halfmann — TU darmstadt, starße xy 204777777
We demonstrate significant enhancement of four-wave mixing (FWM)in coherently driven mercury isotopes to generate vacuum-ultraviolet radiation at 125 nm. The enhancement is accomplished by preparation of the mercury atoms in a state of maximum coherence, i.e. maximum nonlinear-optical polarization, driven by Stark-chirped rapid adiabatic passage (SCRAP). In this technique a pump laser at 313 nm excites the two-photon transition between the ground state 6s2 1S0 and the target state 7s 1S0 in mercury. A strong, off-resonant radiation field at 1064 nm generates dynamic Stark shifts. These Stark shifts induce a rapid adiabatic passage process on the two-photon transition. The maximum nonlinear-optical polarization induced by SCRAP permits efficient FWM of the pump laser and an additional probe laser at 626 nm. The efficiency is further enhanced, as the SCRAP process stimulates the complete set of different mercury isotopes to participate in the FWM-process. This enlarges the effective atomic density of the medium. Thus, we observe the generation of radiation at 125 nm enhanced by more than one order of magnitude with respect to conventional frequency conversion. Parallel to the FWM-process, we monitored the evolution of the population in the medium by laser-induced fluorescence. These data demonstrate efficient coherent population transfer by SCRAP.