  We report on the spectroscopic investigation of quantum dot - micropillar
cavities with unprecedented quality factors. We observe a pronounced dependency
of the quality factor on the measurement scheme, and find that significantly
larger quality factors can be extracted in photoreflectance compared to
photoluminescence measurements. While the photoluminescence spectra of the
microcavity resonances feature a Lorentzian lineshape and Q-factors up to
184,000, the reflectance spectra have a Fano-shaped asymmetry and feature
significantly higher Q-factors in excess of 250,000 resulting from a full
saturation of the embedded emitters. The very high quality factors in our
cavities promote strong light-matter coupling with visibilities exceeding 0.5
for a single QD coupled to the cavity mode.
