Abstract
We investigate the interband transitions of self-assembled InAs/GaAs quantum dots by using resonant photoluminescence spectroscopy under strong magnetic field. Well defined resonances are observed in the spectra. A strong anti crossing between two transitions is observed, which cannot be accounted for by a purely excitonic model. The coupling between the mixed exciton-LO phonon states is calculated using the Frohlich Hamiltonian. The excitonic polaron energies as well as the oscillator strengths of the interband transitions are determined. An anticrossing is predicted when two exciton-LO phonon states have close enough energies with phonon occupations which differ by one. A good agreement is found between the calculations and the experimental data evidencing the existence of excitonic polarons.