Photonic microcavity and nanocavity devices with quantum dot active materials combine the strong confinement of photons and the discrete states of electronic carriers. They are promising candidates for small-footprint, high-speed and low-power active optical components, and provide a robust platform for the enhancement of light-matter interactions. This monograph starts with an introduction to the basic concepts of quantum dot active materials and photonic cavity devices, and the potential applications in photonic integrated circuits and quantum information processing. Then the material...