Micro-cavity semiconductor lasers with controlled spontaneous emission

The principle and applications of quantum electrodynamics in microcavity semi-conductor lasers are reviewed. The coupling efficiency of spontaneous emission into a lasing mode and the spontaneous lifetime are modified by various microcavity structures. As a consequence of the increased coupling efficiency, those microcavity semi-conductor lasers are expected to feature a low threshold current, high quantum efficiency and broad modulation bandwidth. One remarkable result of the increased coupling efficiency is lasing without inversion. The other is intensity squeezing at any pump rate.