Berlin 2012 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 79: Experimental methods
O 79.5: Vortrag
Donnerstag, 29. März 2012, 17:00–17:15, A 060
Characterisation and compression of pJ white-light continuum pulses — •Daniel Wegkamp1, Simon Wall1, Daniele Brida2, Stefano Bonora2, Giulio Cerullo2, Julia Stähler1, and Martin Wolf1 — 1Fritz-Haber-Institute of the MPG, Dep. of Physical Chemistry, Berlin, Germany — 2Politecnico di Milano, Dipartimento di Fisica, Milan, Italy
Pump-probe-spectroscopy using ultrashort laser pulses allows access to the temporal evolution of electron and lattice dynamics. Probing the system in spectral regions that differ from the pump wavelength can give additional insights into those dynamics. White-light continuum pulses enable probing of wide spectral regions without the need of tuning the light source and their bandwidth enables the generation of ultrashort pulses for pump-probe experiments. Compression of the white-light pulses allows us to measure spectrally resolved as well as integrated without the loss of temporal resolution and, furthermore, the pulses may be incorporated in nonlinear optical probing schemes. White-light pulses are generated by self-phase modulation due to focusing of 40 fs laser pulses (800nm, 300 kHz Ti:Sa amplifier system) into a YAG crystal. To compress the pulses we measure the wavelength-dependent group delay in a simple pump-probe-setup. On this basis, we compensate for the phase of the laser pulse by adapting a deformable mirror, which is placed in the fourier-plane of a 4-f-compressor. Near transform-limited pulses of about 10 fs duration are achieved. These are applied to measure the ultrafast dynamics of VO2 below and above the threshold for the photoinduced phase transition.