Dephasing of Mollow Triplet Sideband Emission of a Resonantly Driven Quantum Dot in a Microcavity

Detailed properties of resonance fluorescence from a single quantum dot in a micropillar cavity are investigated, with particular focus on emission coherence in dependence on optical driving field power and detuning. Power-dependent series over a wide range could trace characteristic Mollow triplet spectra with large Rabi splittings of $\mathrm{\mid }\mathrm{\Omega }\mathrm{\mid }\le 15$ GHz. In particular, the effect of dephasing in terms of systematic spectral broadening $\propto {\mathrm{\Omega }}^2$ of the Mollow sidebands is observed as a strong fingerprint of excitation-induced dephasing. Our results are in excellent agreement with predictions of a recently presented model on phonon-dressed QD Mollow triplet emission in the cavity-QED regime.