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

TL;DR

This paper accurately measures the exciton fraction in high-Q GaAs/AlGaAs microcavities using transfer-matrix modeling, combining multiple optical techniques to improve precision and compare with low-Q structures.

Contribution

It introduces a comprehensive calibration method for exciton fraction in high-Q microcavities, addressing challenges in visibility of the upper polariton and integrating various measurement techniques.

Findings

Exciton fraction varies with lower polariton energy.

High-Q microcavities require careful calibration for accurate exciton fraction.

Comparison with low-Q structures validates the modeling approach.

Abstract

We present a careful calibration of the exciton fraction of polaritons in high-$Q$ ($\sim 300,000$), long-lifetime ($\sim 300$ 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.