MICROSCOPIC THEORY OF THE TIME-DEPENDENT OPTICAL-RESPONSE FROM QUANTUM-WELLS

The reflected and transmitted energy flux corresponding to the linear response of a quantum well (QW) is calculated analytically for the cas es of monochromatic and pulsed incident radiation normal to the QW pla ne. The light-matter interaction has been taken to all orders of pertu rbation theory, resulting in the appearance of radiative broadening in the expressions for the secondary fields. Three time scales determine the decay of the response after the pulse excitation while the quantu m beats are superimposed on the exponentially decaying contributions a t the frequency which (i) equals detuning from the electronic transiti on or (ii) corresponds to a characteristic excitation in the system.