Microcavity Polaritons in Materials with Weak Intermolecular Interaction

We analyze the optical properties of exciton-polaritons in a microcavity, which utilizes materials with broad and dispersionless electronic resonances as the optically active semiconductor. The excitations in such non-cavity materials are localized, and for these excitations the wave vector is not a “good” quantum number. We show that in a microcavity as a result of strong light–matter coupling two polariton branches appear, which are analogous to the cavity-polariton branches observed in inorganic semiconductor structures. However, the polariton branches only exist in certain restricted intervals of wave vectors. We then show that in such materials the majority of the electronic excited states do not strongly couple to the cavity photon, and these states can be regarded as essentially incoherent. Based on these results, we discuss some peculiarities of the dynamics of excitations in a microcavity containing such type of materials.