  The non-sinusoidal character oscillations appear in the transmitted,
reflected and absorbed light fluxes when light pulses irradiate a semiconductor
quantum well (QW), containing a large number of the equidistant energy levels
of electronic excitations. A damping echo of the exciting pulse appears through
the time intervals $2\pi\hbar/\Delta E$ in the case of the very short light
pulses $\gamma_l^{-1}\ll\hbar/\Delta E$.
