Berlin 2014 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 46: Ultrashort laser pulses II

Q 46.3: Talk

Thursday, March 20, 2014, 14:30–14:45, DO26 207

Measurement and optimization of the temporal resolution in a broadband transient spectrometer — •Emanuel Wittmann, Roland Wilcken, Sebastian Wiegner, Maximilian Bradler, and Eberhard Riedle — LS für BioMolekulare Optik, LMU München

With tunable UV or visible excitation and continuum probe pulses molecular dynamics are measured with sub-50 fs resolution [1]. Particularly for UV excitation the optimization of the pump pulse compression is far from trivial. The coherent artifact contained in the measurement signal is heavily intermingled with the molecular response. We recently showed that two-photon-absorption can be used to characterize the UV pulses - unfortunately at the price of additional complexity in the experiment. We now investigate the use of the continuum to characterize the UV pulses in-situ and find: a) the proper crystals, glasses or liquids have to be chosen to ensure pure absorptive TPA signals and to avoid dispersive contributions that complicate the interpretation. b) no single material covers the more than octave wide probe spectrum, but suitable combinations can be found. c) with these materials a temporal scan can be largely avoided as the width of the time resolved crosscorrelation spectrum correlates to the temporal width. d) with the newly developed characterization a minimization of the pump pulse length and the temporal resolution can be performed within minutes.

[1] U. Megerle, I. Pugliesi, C. Schriever, C. F. Sailer, E. Riedle, Appl. Phys. B 96, 215 (2009).

[2] C. Homann, N. Krebs, E. Riedle, Appl. Phys. B 1046, 783 (2011).