Stuttgart 2012 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 5: Ultrakurze Laserpulse: Erzeugung 1

Q 5.5: Talk

Monday, March 12, 2012, 11:30–11:45, V38.01

Tunable 30 fs deep UV-pulses by chirp-management in the visible — •Peter Lang, Christian Homann, and Eberhard Riedle — BioMolekulare Optik, LMU München

We generate deep UV (DUV) pulses by chirp-optimized frequency doubling and sum frequency mixing that directly yields compressed output pulses with durations around 30 fs in the wavelength range of 190 - 240 nm. Tunable pulses from a NOPA with a tuning range of 450 - 750 nm are negatively chirped in the visible with a fused silica prism compressor and focused into a BBO crystal for frequency doubling. The DUV pulses are generated by sum frequency mixing with the TiSa fundamental. The compression of the DUV pulses is achieved by solely changing the length of the NOPA prism compressor in the visible. Changing the path length of the fundamental laser pulse with the same delay stage allows to maintain the temporal overlap of both pulses. Furthermore the use of a delay line for the prism compressor allows to vary the chirp over a wide range without loosing the spatial overlap. The DUV pulses have Fourier limits below 25 fs given by the acceptance bandwidth of the sum mixing crystal. Compared to the generation of high harmonics in argon cells the sum frequency mixing with very thin BBOs is readily achieved. We generate ultrashort pulses without the need for UV compression and keep the number of mirrors and the path length in the UV minimal. The resulting DUV energy above 200 nJ is high enough for time resolved photo-electron spectroscopy and pump-probe measurements in solution.