Four-wave mixing in intersubband transitions of a semiconductor quantum well structure

We study theoretically the phenomenon of four-wave mixing in intersubband transitions of a symmetric double quantum well structure. In the theoretical model we consider two quantum well subbands that are coupled by a strong pump electromagnetic field and a weak probe electromagnetic field, taking into account the effects of electron-electron interactions. For the description of the system dynamics we use the density matrix equations obtained from the effective nonlinear Bloch equations. These equations are solved numerically for a realistic semiconductor quantum well structure GaAs/AlGaAs. We show that the four-wave mixing spectrum can be significantly dependent on the frequency and the intensity of the pump field and on electron sheet density.