ABC...z Seminar Series: Monday, February 5th: Nonlinear THz free-electron laser spectroscopy of graphene and GaAs quantum wells

Event Date: 

Monday, February 5, 2018 - 2:00pm

Event Location: 

  • Broida 3302
  • ABC...z Seminar Series

This talk reviews some recent experiments ongraphene and on GaAs quantum wells using FEL-based strong THz fields.

In graphene, we have investigated the pump-inducedanisotropy of the carrier distribution upon excitation with linearly polarizedlight. Since optical-phonon scattering is suppressed at THz frequencies and lowtemperatures, we observe the decay of this anisotropy to be very slow, as longas several ps, which is theoretically explained by non-collinear Coulombscattering. We also report on degenerate four-wave mixing experiments inLandau-quantized graphene to investigate the induced coherent polarization.

In GaAs quantum wells,intense narrow-band THz fields are exploited for dressing elementary electronicexcitations. We will address THz-induced dressing of excitons, exciton-polaritons, andintersubband transitions. 

Harald Schneider, Division ofSpectroscopy, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany