München 2004 – scientific programme

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Q: Quantenoptik und Photonik

Q 19: Poster Festkörper- und Halbleiterlaser

Q 19.6: Poster

Tuesday, March 23, 2004, 14:00–16:00, Schellingstr. 3

A Raman laser system for the Rb-87 D2 line — •Jochen Kronjäger, Michael Erhard, Holger Schmaljohann, Kai Bongs, and Klaus Sengstock — Institut f. Laserphysik, Luruper Chaussee 149, D-22761 Hamburg

Raman transitions are a powerful tool for probing and manipulating atoms and molecules. In our Rb spinor BEC experiment, we apply Raman transitions for coherent population transfer between the hyperfine ground states. A Raman transition requires a bichromatic coherent light field, i.e. two lasers with a certain frequency offset but fixed phase relationship [1].

Our Raman laser system consists of two extended cavity diode lasers: one (the master) runs free or can be frequency stabilized by standard spectroscopic techniques, the other one (slave) is phase stabilized at a frequency offset of about 6.8 GHz relative to the master. The fixed phase relationship between the two is maintained by an optical phase locked loop (OPLL) comprising three steps of phase detection: a fast photodiode, a microwave mixer and a digital phase/frequency discriminator (PFD). The monotonic response of the PFD provides an extended capture range of the servo loop (+/-10 MHz).

The Raman laser systems has been used to measure a mixed spin channel Feshbach resonance of Rb-87 [2]. Future plans include coherent coupling of the F=2 (antiferromagnetic) and F=1 (ferromagnetic) states of a spinor condensate and the preparation of filled solitons.

[1] M. Prevedelli et al., Appl. Phys. B 60, 241-248 (1995)

[2] M. Erhard et al., cond-mat/0309318 (2003)