Applications of III–V Semiconductor Quantum Dots in Optoelectronic Devices

Semiconductor quantum dots (QDs) have the potential to improve the properties of optical devices such as semiconductor lasers, semiconductor optical amplifiers, and so on. They are of great interest due to their delta‐function‐like density of states, in contrast to conventional bulk semiconductors which have a density of states with a parabolic shape. In particular, if QDs are introduced in semiconductor lasers as gain media, they improve their performance. For example, the temperature dependence of the threshold current in a semiconductor laser will disappear because the injected carriers at the QD's discrete energy levels are not allowed to redistribute, even if the temperature increases. In this chapter, QD lasers are studied for two representative wavelengths, 1.3 and 1.55 µm, used in fiber‐optic communication systems.