Squeezing and controlled spontaneous emission in semiconductor lasers

Summary form only given. A constant-current driven semiconductor laser has a sub-Poissonian internal pump noise and thus produces a number-phase squeezed state instead of a coherent state. The measured photon number (intensity) noise was -8.6 dB below the shot noise value. The authors review the principle and the potential applications of squeezed state generation by semiconductor lasers. They discuss control of spontaneous emission in a semiconductor laser. Spontaneous emission in not an immutable property of an atom but is a consequence of atom-vacuum field (quantum mechanical zero-point fluctuation) coupling. If the intensity of a vacuum field fluctuation is modified by a cavity wall, spontaneous emission is either enhanced or suppressed. The principle is known as a cavity quantum electrodynamic effect. A surface emitting microcavity semiconductor laser has enhanced spontaneous emission rate into a lasing mode and suppressed spontaneous emission rate into nonlasing spurious modes which leads to an increased spontaneous emission coefficient and decreased lasing threshold. Various applications of such a microcavity effect are discussed.