Nonlinear optical spectroscopy of biexcitons and excitonic polaritons in CuCl (CuBr)

Copper halides (especially CuCl) have played an important role in the development of nonlinear optical spectroscopy. The binding energies of excitons and of biexcitons are so large that the optical response of these materials and its dynamics could be fully described in the frame of these quasi-particle states and of their mutual interactions. We shall go through the different steps of the development of this research and present the contribution of the Strasbourg Group to this activity.