InAs/GaAs quantum dot lasers

Quantum dot (QD) structures are believed to provide a promising way for a new generation of injection lasers. Intrinsic properties of QD lasers such as strongly increased gain and differential gain, ultra low threshold current density and high characteristic temperature are theoretically predicted. Some of these characteristics are experimentally verified at liquid nitrogen temperatures on realistic device structures. Due to small dot densities in the range of 5/spl times/10/sup 10/ cm/sup -2/ single layer quantum dot (SLQD) lasers exhibit a very small confinement factor and thus lack the ability to serve as high power lasers. The dot density within the active region can be increased by stacking the dot layers vertically on top of each other. The threshold current behaviour of a stacked QD laser is compared with that of a single layer QD laser. We demonstrate for the first time room temperature lasing of a stacked QD laser via the QD ground state.