2013-03-13, Schmidt, Christian, Mayer, Bernhard, Junginger, Friederike, Rebholz, Marc, Grupp, Alexander, Brida, Daniele, Huber, Rupert, Leitenstorfer, Alfred, Pashkin, Alexej

Ultraintense few-cycle THz pulses are employed to study the nonlinear response of graphite. A phase sensitive 2D spectroscopy setup is capable of detecting pump-induced transient changes as well as multi-wave mixing processes. The observed strong THz-pump THz-probe signals provide insight into ultrafast dynamics and the spectral response of the low-energy carriers. Here we report the observation of a pump-induced transmission in graphite. The relaxation dynamics shows three distinct time scales, which are assigned to carrier thermalization, phonon emission and a slow cooling down back to equilibrium.