Long-wavelength lasers using GaAs-based quantum dots

Modern trends in design of semiconductor lasers are addressed. Nanoscale coherent inclusions of narrower bandgap semiconductor in a wider gap semiconductor matrix, or quantum dots (QDs), are designed as a new type of active medium of injection lasers. QDs give a possibility to extend the wavelength range of heterostructure lasers on GaAs substrates to 1.3 micrometers and beyond and improve their device performance. 330 mW CW 1.3 micrometers single mode continuous wave (CW) edge emitters and 1.2 mW CW vertical-cavity surface- emitting lasers (VCSELs) are realized. Long operation lifetimes and other competitive device parameters are demonstrated. Novel device designs are proposed. In one concept high-order mode filtering in structures with periodically modulated refractive index containing a defect allows realization of stable narrow beam divergence fundamental model lasing both in edge-emitters and in VCSELs. In a different novel design, light propagates at some angle with respect to multilayer interference mirrors (MIR), and the MIRs and the cavity are calculated for the tilted photon incidence. Tilted cavity laser (TCL) gives wavelength-stabilized operation in edge and (or) in surface direction and does not require materials having high refractive index difference. New generations of semiconductor optical amplifiers, photodetectors, optical fibers, etc. may become a reality.