Terahertz Physics of Semiconductor Heterostructures

Modern time domain THz spectroscopy provides unprecedented time resolution as well as phase information which allows studying many fundamental resonances. For semiconductor nanostructures the underlying physics of the quantized states can be observed. The THz interaction with the quantized electrons in quantum wells is studied and from the free induction decay the coherence times are extracted. The population lifetimes are obtained from nonlinear experiments which also demonstrate the strong influence of electron-electron interaction. THz Quantum Cascade lasers are investigated to obtain the gain band width and dispersion. THz pulse amplification and ultrashort pulse generation from Quantum Cascade structures is demonstrated.