ABSTRACT
In general, the laser emission is based on population inversion of the electronic states, which contribute to the radiative recombination. For semiconductor lasers, it has been realized early (Dingle and Henry, 1976) that the carrier conœnement in quantum wells leads to improved laser properties, like a laser threshold reduction. ›e successful demonstration of this e˜ect was based on advances in the material growth (Tsang, 1982). ›e use of quantum dots (QDs) as an active material promises even greater beneœts. First of all, one gains more freedom to engineer the emission wavelength (Bimberg et al., 1999). Another advantage is the enhancement of the single-particle density of states. For states experiencing a carrier conœnement in all three dimensions, discrete electronic energies similar to the spectrum of atomic systems are obtained. ›is has led to predictions of further increased eµciency for laser applications, which are based on less temperature-dependent operational parameters (Arakawa and Sakaki, 1982), further reduced threshold currents
and higher di˜erential gain (Asada et al., 1986), higher modulation bandwidth (Kim et al., 2004) and reduced anti-guiding e˜ects (Newell et al., 1999), as well as a reduced sensitivity to material defects. Also, the miniaturization of the active material in connection with new microcavity laser resonators opens the door for novel applications in quantum information technologies.
