Berlin 2001 – scientific programme

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Q: Quantenoptik

Q 22: Poster: Quantum Effects

Q 22.3: Poster

Thursday, April 5, 2001, 12:30–15:00, AT2

Efficient Raman side band generation in a coherent atomic medium — •A. F. Huss, N. Peer, R. Lammegger, E. A. Korsunsky, and L. Windholz — Institut f. Experimentalphysik, Technische Universität Graz, Österreich

Excitation of a Λ-type atomic level system by two resonant laser frequencies ω₁ and ω₂ results in the creation of a superposition dark state via destructive quantum interference. Preparation of atoms in this dark state through optical pumping leads to reduced absorption and an enhanced nonlinear optical susceptibility, thus nonlinear optical processes become efficient. Atoms in this dark state act as a local oscillator at frequency ω₁₂ = ω₂ − ω₁. A third frequency ω₃ beats against the local oscillator producing sum- and difference frequencies ω₃ ± n ω₁₂, i.e. Raman side bands.

We experimentally demonstrate the generation of Raman side bands in sodium atomic vapor excited on D1 line. First order side bands for ω₁, ω₂ and up to third order side bands for ω₃ have been observed. A small dark state decay rate of only a few kHz ensures high generation efficiency even at low input light power (10 µ W).