Nonlinear THz free-electron laser spectroscopy of graphene and GaAs quantum wells


Nonlinear THz free-electron laser spectroscopy of graphene and GaAs quantum wells

Schneider, H.

This talk reviews some recent experiments on graphene and on GaAs quantum wells using FEL-based strong THz fields.
In graphene, we have investigated the pump-induced anisotropy of the carrier distribution upon excitation with linearly polarized light. Since optical-phonon scattering is suppressed at THz frequencies and low temperatures, we observe the decay of this anisotropy to be very slow, as long as several ps, which is theoretically explained by non-collinear Coulomb scattering. We also report on degenerate four-wave mixing experiments in Landau-quantized graphene to investigate the induced coherent polarization. In GaAs quantum wells, intense narrow-band THz fields are exploited for dressing elementary electronic excitations. We will address THz-induced dressing of excitons, exciton-polaritons, and intersubband transitions.

Keywords: Graphene; intersubband; nonlinear terahertz spectroscopy

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Publ.-Id: 27802