Coherent dynamics at the semiconductor band edge

I. Balslev, A. Stahl

Á. Stáhl

Brian S. Wherrett, N. A. Higgins

Abstract Detailed comparisons are made of the results of two approaches to the problem of nonlinear refraction at frequencies just below the band edge in semiconductors. The physical origin o f the nonlinear dispersion is taken to be direct saturation of independent, T2-broadened band states in the first model discussed. In the second model the refraction associated with a dynamic Burstein-Moss shift of the absorption edge is considered. Both models predict an extremely large nonlinearity, X(3) ≈ 1 e. s. u., of importance in the field of dispersive optical bistability and consistent with experimental observations of bistability, two-beam differential gain and four-wave mixing.

Stefan W. Koch, T. Meier, T. Stroucken +4 more

Stephan Glutsch, U. Siegner, D. S. Chemla

We study the dynamics of coherent emission of a semiconductor within the framework of the semiconductor Bloch equations, both in the time domain 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 from continuum states of a semiconductor has the same dynamical properties 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 macroscopic 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 polarization, the wavelength of the exciting light can still be neglected.

D. Hägele, J. Hübner, Wolfgang W. Rühle +1 more