Coherent and incoherent intersubband dynamics

Presents time-resolved measurements of photoinduced intersubband absorption in an undoped GaAs/AlGaAs coupled quantum well excited by an ultrashort interband optical pulse. An interband pump pulse injects electrons into the first and second subband of an undoped asymmetric double quantum well (ADQW) with a level spacing smaller than the LO phonon energy. The time evolution of the electron population in these two subbands is monitored by probing the MIR intersubband transitions to a third (empty) subband.