Coherent and incoherent excitation of two-dimensional plasmons in AlGaAs/GaAs quantum wells by femtosecond laser pulses

摘要

We have investigated terahertz radiation from two-dimensional plasmons in a doped GaAs/AlGaAs single quantum well by time-resolved THz emission spectroscopy.By varying the excitation energy and power we found two different excitation mechanisms are responsible for exciting plasmons; i.e. coherent instantaneous polarizations and incoherent current surge and/or thermal process.