Quantum-dot development pursues new applications

A review. The modulation response of quantum-dot (QD) lasers has remained limited in the 1300 to 1550 nm wavelength region. However, new applications have taken advantage of the unique features of quantum dots. The temp. dependence of the QD laser threshold current can be much better than quantum-well lasers because the electronic levels in the conduction band are spaced by more than the Boltzmann energy, kT, and thus little change in population distribution occurs at room temp. Another advantage of QD lasers is the possibility of engineering the line-width-enhancement factor or gain-phase coupling.