Characterization, Modeling, And Design Of Microcavity Exciton-Polariton Samples

Exciton-polaritons are particles combining the aspects of solid matter with light. They interact and scatter off one another, while also having a very light effective mass. They thermalize well, but are also bosons, meaning they can condense into Bose-Einstein condensates at much higher temperatures than many other systems. They are typically generated in semiconductor structures grown in extremely precise molecular beam epitaxy machines. Very high quality samples are commonplace, and long polariton lifetimes over 100 ps are observed. However, when the samples are of such high quality, the polaritons may no longer be easily observed in reflectivity measurements, because they have surpassed the resolution of normal laboratory spectrometers. Also, one of the two polariton states, known as the upper polariton, is no longer visible in standard photoluminescence measurements, because its decay is dominated by down-scattering into lower polariton states. This has been a consistent problem for calculating the exciton fraction, which is an essential parameter in many-body theories that include the polariton-polariton interactions. In this work, I present my work on accurate calculation of the exciton fraction of polaritons in semiconductor microcavities. This work includes redesign of several experiments, creation of a photoluminescence excitation measurement setup, which allows detection of the upper polariton, and simulation of the electromagnetic properties of polariton microcavity structures using the transfer-matrix method. These simulations show great success, and may be used for designing future samples. Additionally, I present work on cavity structures with transition-metal dichalcogenide monolayers, as a means towards room temperature polariton physics.