Berlin 2001 – wissenschaftliches Programm

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Q: Quantenoptik

Q 23: Poster: Application of Short Pulses

Q 23.8: Poster

Donnerstag, 5. April 2001, 12:30–15:00, AT2

Autocorrelation measurements of sub-50 fs UV pulses — •K. Stock, M. Beutter, J, Piel, and E. Riedle — LS BioMolekulare Optik, Sektion Physik, Ludwig-Maximilians-Universitaet Muenchen

The determination of the pulse length of sub-50 fs UV pulses can so far not be made by second harmonic autocorrelation measurements in thin nonlinear crystals since crystals with suitable phase matching and transmission are not yet available. Crosscorrelation measurements can produce largely erroneous results due to the limited phase matching bandwidth. Instead the use of transient absorption and two-photon photoconductivity in home built devices has been reported, these methods are however not readily implemented as standard tools. We have therefore tested a number of commercially available devices for their suitability. We were able to produce a correlation trace with an UV sensitive flame detector, however a very long scan time is needed due to the electronic response characteristic of the unit. Diamond based devices are quite promising and recently a unit based on the photoconductivity and a vacuum photodiode became available. The first showed a purely linear response at photon energies well below the band gap, even for intensities leading to long term damage. The second easily produced an autocorrelation trace with 400 nm pulses, however the achievable temporal resolution was limited by the intrinsic response of the diamond photocathode.