Optics of semiconductor microcavities

Abstract

In this work the interactions of carriers, electrons and holes, and photons in a semiconductor microcavity are studied in the perturbative and the nonperturbative regimes. In the perturbative regime, modification of the spontaneous emission rate of carriers by a semiconductor microcavity is investigated with 100-nm-thick bulk GaAs. Reabsorption makes the cavity-mode photoluminescence (PL) decay much faster than the square of the carrier density. Here reabsorption distortion is avoided by collecting PL that escapes the microcavity directly without multiple reflections using a ZnSe prism glued to the top mirror. Removal of most of the bottom mirror decreases the true carrier decay rate by only ≈25%, showing that the large enhancements deduced from cavity-mode PL are incorrect. A fully quantum mechanical computation including guided modes corroborates this conclusion. The prism technique could be used to study carrier dynamics and competition between guided and cavity modes in microcavities below and near threshold. In the nonperturbative regime, normal mode coupling (NMC) between the quantum-well excitonic susceptibility and photons is studied. In cw linear experiments, the effects of varying cavity finesse and exciton absorption linewidth and line shape and their contributions to the linewidth of NMC peaks are investigated and compared with the experiments. It is shown that all of the observed experimental features can be explained by a linear dispersion theory model that incorporates the experimental excitonic absorption spectrum of the quantum well. Some nonlinear features of NMC obtained from time-resolved measurements are also studied and discussed.