Resonant saturation laser spectroscopy of a single self-assembled quantum dot

We performed high resolution resonant laser spectroscopy on a single self-assembled quantum dot (QD) at liquid He temperatures. We explore the two-level nature of the QD excitonic transition through the investigation of its behavior as a function of the laser power. The quantum ground state exciton absorption peak size diminishes with increasing power while its width increases. Fitting these dependencies to the predictions of a two-level atom model we extract unambiguously a radiative lifetime of 660 ps, a residual collisional broadening about View the MathML source as well as the spectral fluctuation View the MathML source. We find that at high power the line width of the exciton absorption is essentially given by the Rabi frequency.