COHERENT THZ PLASMONS IN GAAS - TRANSITION FROM PURE PLASMONS TO COUPLED PLASMON-PHONON MODES

摘要

We report on the observation of coherent THz plasmons in GaAs using the femtosecond time-resolved pump-probe technique. Tile samples are GaAs/AlGaAs modulation doped single heterostructures with a depletion field below the PD-channel in the intrinsic GaAs substrate. For the first time, several coherent oscillations !up to five full periods) are clearly visible in the frequency range of 1.5 to 5 THz. The observed oscillation frequencies increase with Increasing carrier densities. Our experimental data are in good agreement with theoretical Ensemble-Monte-Carlo simulations. [References: 4]