Excitonic radius in the cavity polariton in the regime of very strong coupling

It is shown that the excitonic cavity polariton undergoes dramatic;changes when the vacuum Rabi splitting energy becomes comparable to the exciton binding energy. The radius of the exciton becomes a strong function of the detuning, and, in screened systems, the coupling with the photons can preclude the Mott transition. (C) 2001 Published by Elsevier Science Ltd.