Measurement of exciton fraction of microcavity exciton-polaritons using transfer-matrix modeling

We present a careful calibration of the exciton fraction of polaritons in high-Q (∼ 300,000), long-lifetime (∼ 300 ps), GaAs/AlGaAs microcavities.This is a crucial parameter for many-body theories which include the polariton-polariton interactions.It is much harder to establish this number in high-Q structures compared to low-Q structures, because the upper polariton is nearly invisible in high-Q cavities.We present a combination of photoluminescence, photoluminescence excitation, and reflectivity measurements to highly constrain the fit model, and compare the results of this model to the results from low-Q structures.We present a fitted curve of exciton fraction as a function of the lower polariton energy for multiple samples which have been used in prior experiments.