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Q: Quantenoptik und Photonik
Q 33: Poster Nichtlineare Optik und Atomoptik
Q 33.2: Poster
Dienstag, 14. März 2006, 16:30–18:30, Labsaal
Enhanced Four-Wave Mixing in mercury isotopes, prepared by Stark-chirped rapid adiabatic passage — •Martin Oberst, Jens Klein und Thomas Halfmann — Erwin-Schrödinger-Str., 67653 Kaiserslautern
We demonstrate significant enhancement of four-wave mixing 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 serve to induce a rapid adiabatic passage process on the two-photon transition. The maximum nonlinear-optical polarization induced by SCRAP permits efficient four-wave mixing of a pump laser and an additional probe laser at 626 nm. The efficiency is further enhanced, as the SCRAP process allows to stimulate the complete set of different mercury isotopes to participate in the frequency conversion process. This enlarges the effective atomic density of the medium. Thus, we observe the generation of vacuum-ultraviolet radiation at 125 nm enhanced by more than one order of magnitude with respect to conventional frequency conversion. Parallel to the frequency conversion process, we monitored the evolution of the population in the medium by laser-induced fluorescence. These data demonstrate efficient coherent population transfer by SCRAP.