Photon echo and exchange effects in quantum-confined semiconductors

Photon echo calculations for semiconductor quantum dots and quantum wells are presented and the role of the Fermion exchange effects is emphasized. The echoes for the quantum-dot systems arise as a consequence of the inhomogeneous broadening due to the dot size distribution. It is shown that quantum beats are superimposed to the echo signals, suggesting a sensitive way to determine the energy level separation in these systems. In semiconductor quantum wells the inhomogeneous broadening is caused by the continuum of states for the unconfined directions of electron motion. To investigate this case the semiconductor Bloch equations are generalized to include confinement induced valence band mixing. Photon echo and phase conjugate signals are computed with and without band mixing effects. The significance of the exchange contributions is analyzed for the different configurations.