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MO: Fachverband Molekülphysik

MO 18: Femtosekundenspektroskopie

MO 18.12: Poster

Tuesday, March 11, 2008, 14:00–19:00, Poster C1

Phase modulation of ulstrashort laser pulses by rotational wave packets — •Raphael Kuhnen and Bernd v. Issendorff — Universität Freiburg, physikalisches Institut, Stefan-Meier-Strasse 19, D-79104 Freiburg

Molecular rotational wave packets introduce a time dependent phase modulation to ultrashort optical pulses. This phase modulation can be imaged by observing the spectrum of a probe laser pulse sent with a tunable delay to an alignment pulse.
The processes affecting the probe laser pulse depend on the polarisation of the pump pulse. This influence as well as the temporal evolution of the rotational wave packets can be observed by recording the transmitted spectrum of a 400nm, linear polarized, laser pulse depending on the pump-probe delay as well as the rotation angle of a quarter-wave-plate in the pump-beam.
It is possible to tune the phase in a way that the spectrum of the laser pulse is broadened and shifted by raman scattering. As a result it is possible to introduce a negative chirp to the probe laser pulse and to reduce the pulse duration below 25 fs.

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(4) R. Torres et al., Phys. Rev. A, 72, 023420 (2005)