Optical linewidths in an individual quantum dot

On the basis of lattice relaxation due to the electron acoustic phonon coupling, we theoretically analyze the homogeneous optical linewidths of a single quantum dot. The calculated result based on a nonstrong-coupling approximation shows that in a considerable range of temperatures the homogeneous linewidth can be expressed in terms of ${\Gamma }_h={\Gamma }_0+AT,$ and the size dependence is characterized by ${\Gamma }_0\propto 1/R$ and $A\propto {1/R}^2,$ where T is the temperature and R is the quantum dot radius. While this result qualitatively agrees well with the available experiments on exciton dephasing, it straightforwardly implies the infrared optical properties due to intraband transitions with transition energy around 100 meV.