Ultrafast dynamics of confined and localised excitons and biexcitons in low-dimensional semiconductors

Coherent optical spectroscopy in the form of nonlinear transient four-wave mixing (TFWM) and linear resonant Rayleigh scattering (RRS) has been applied to investigate the exciton dynamics of low-dimensional semiconductor heterostructures. The dephasing times of excitons are determined from the decay of the spectrally resolved non- linear signal as a function of the delay between the incident pulses in a two-beam TFWM experiment, and from the real time analysis of single speckles in RRS experiments (pure dephasing).

From the density- and temperature- dependence of the dephasing times the exciton-exciton and the exciton-phonon interactions are determined. The degree of coherence of the secondary emission is determined from the speckle analysis.