S. Glutsch et al., SPATIOTEMPORAL DYNAMICS OF PHOTON-ECHOES FROM CONTINUUM STATES IN SEMICONDUCTORS, Physical review. B, Condensed matter, 52(7), 1995, pp. 4941-4950
We study the dynamics of coherent emission of a semiconductor within t
he framework of the semiconductor Bloch equations, both in the time do
main and in real space for various excitation conditions. We find that
the spatial properties of the four-wave-mixing (FWM) response reflect
the well-known temporal dynamics. For excitation high above the band
edge, the FWM signal is emitted as a photon echo. This photon echo fro
m continuum states of a semiconductor has the same dynamical propertie
s as a photon echo from inhomogeneously broadened uncoupled two-level
systems. However, unlike the case of two-level atoms, the polarization
of the photon echo from the semiconductor continuum extends over macr
oscopic distances in real space. The implications of the large spatial
extent of the photon echo polarization are discussed. In particular,
we show that, in spite of the macroscopic size of the photon echo pola
rization, the wavelength of the exciting light can still be neglected.