Contents I. Introduction
Recent achievements in optical communication initiated an increasing demand for a new concept of optical transmitters, especially lasers. This concept should provide low threshold currents, high optical gain, higher modulation bandwidths, narrower spectral linewidths and reduced temperature sensitivity of lasers [1]. In particular, quantum wire (QWR) and quantum-dot (QD) lasers are expected to satisfy these requirements to a much larger extent than conventional heterostructure or quantum-well (QW) lasers. Improved performance of QWR lasers is achieved by a theoretically infinite density of states (DOS) at the band edge as well as by a symmetrization of conduction and valence-subband effective masses [2]. QD lasers should exhibit better performance than QWR due to additional carrier confinement. However, QDs can not be fabricated in a well-controlled manner, as it is the case with QW or QWR. Instead, QDs are commonly realized by self-organized growth, which leads to QDs statistically distributed in size and area.
