Abstract
We present a review on the excitonic homogeneous linewidth, with an emphasis on original experiments by means of nonlinear spectral hole-burning. We address three specific aspects of the excitonic homogeneous broadening: (i) the variation of the homogeneous linewidth with the sonication energy, revealing the influence of extrinsic processes such as exciton-defect interactions, (ii) the collision-induced broadening due to exciton-exciton interactions, investigated by power-dependent measurements, and (iii) the phonon-induced dephasing due to exciton-phonon interactions, deduced from temperature-dependent experiments. We discuss the specific properties of one-dimensional excitons in carbon nanotubes in the context of the homogeneous broadening.