Characterization of High-Q Microcavity Quantum Wells

The development of high-Q microcavity quantum well samples has led to long lifetime polaritons, thus allowing for long distance propagation of polaritons. However, long lifetime polaritons have very narrow line widths, as a result we can no longer resolve the polariton branches in the reflectivity spectrum of these samples. This makes accurately determining the detuning of polariton populations difficult. Accurate detuning information is essential for quantitative work involving absolute density of the polariton population. In this work, we will discuss our modern characterization techniques. We have two methods which we currently use. One method involves fitting large angle dispersion curves of the lower polariton with the theoretical predictions of a two state model. The other method involves measuring accurate dielectric functions for our materials, and then comparing experimental reflectivity data to the predictions of a transfer matrix model to determine the cavity mode. Both of these methods depend on the measurement of the rabbi splitting by photoluminescent emission scans. We found these two methods agree well with each other.