Transient four-wave mixing in intersubband transitions of semiconductor quantum wells

In this work we theoretically study the transient four-wave mixing (FWM) spectrum in a symmetric double semiconductor quantum well structure. The system interacts with a near resonant strong pump field and is probed with a weak field. We assume that the rectangular pump and probe fields interact with two quantum well subbands. In order to describe the system, we use the modified density matrix equations containing terms which owe their presence to the electron–electron interactions. The density matrix equations are solved numerically, for a GaAs/AlGaAs semiconductor quantum well structure, for different moments in the time interval, until the system reaches its steady state. We consider the effects of electron sheet density and pump field frequency on the transient FWM spectrum. A physical interpretation of some spectral characteristics is attempted, via a dressed-state analysis of the semiconductor quantum well coupled to the strong pump field.