GaAs-based long-wavelength lasers

The present paper reviews recent achievements in the fabrication of diode lasers for the near-infrared range on GaAs substrates. 1.3 mu m light emitters are currently widely. used in fibre-optic communication systems. GaAs-based devices are potentially advantageous compared to their InGaAsP counterparts in several aspects, such as improvement of thermal stability, possibility to grow vertical-cavity surface-emitting lasers in a single growth run and the use of large-area high-quality inexpensive GaAs substrates. Three main approaches have been suggested so far to achieve the 1.3 mu m emission from structures grown on GaAs substrates. They are InGaAs and GaAsSb quantum wells, GaInAsN quantum wells and InAs/GaAs quantum dots. In the present paper we discuss all these approaches including material growth, optical properties and laser characteristics. The results obtained by these methods are compared and their potential advantages discussed.