Calibration of long-lifetime polariton structures*

In short-lifetime polariton samples both the upper and lower polariton branches can be resolved through white light reflectivity. However, in long-lifetime polariton samples the linewidths are so narrow that they can not be resolved through typical spectroscopy. Additionally, photoluminescence from the upper polaritons can often not be seen at relevant detunings, as the upper polaritons quickly drop down to lower polariton states. As such, the calibration of long-lifetime polariton samples is uniquely challenging compared to short-lifetime polariton samples. In this work, we will show various measurements which demonstrate the cavity lifetime is 100 ps or more, and use this collective set of information to create an accurate calibration of the long-lifetime polariton samples.