Acoustic phonon broadening mechanism in single quantum dot emission

We study the effect of the exciton-acoustic-phonon coupling on the optical homogeneous line shape of confined zero-dimensional excitons and discuss the connection with the so-called pure dephasing effect. On increasing the temperature, the line shape progressively deviates from the expected Lorentzian profile, with the appearance of low energy acoustic-phonon sidebands. The non-Lorentzian line shape and its temperature dependence are theoretically modeled on the basis of the lattice relaxation due to the exciton-acoustic-phonon coupling. This gives a precise description of the underlying mechanism which controls the exciton dephasing.