Pulsed four-wave mixing in intersubband transitions of a symmetric semiconductor quantum well

We study theoretically the phenomenon of pulsed four-wave mixing in intersubband transitions of a symmetric semiconductor double quantum well structure. In the theoretical model we consider two quantum well subbands that are coupled by a strong pump electromagnetic pulse and a weak probe electromagnetic pulse and take 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 specific double GaAs/AlGaAs quantum well structure. We show that the time-integrated four-wave mixing spectrum depends strongly on the frequency and the intensity of the pump field, on the time-delay between the two electromagnetic pulses and on the electron sheet density.