Dispersion law of exciton polaritons in MQW based photonic crystals

Abstract

The exciton polariton dispersion law is analyzed in a one-dimensional multiple-quantum-well based photonic crystal. An effective approach allowing consideration structures with an arbitrary periodic spatial modulation of the dielectric function and the multilevel structure of the exciton spectrum is developed. It is shown that the condition for the Bragg resonance has to be modified to take into account the symmetry of the exciton states and the non-trivial dispersion law for the electromagnetic waves in photonic crystals. For the particular case of a one-level excitonic susceptibility it is shown that the Bragg resonance occurs when the exciton frequency falls at the high-frequency boundary of the photonic band-gap. The polariton's dispersion law is considered. The angular dependence of the spectrum is analyzed. The effect of multiple exciton levels on the polariton spectrum is discussed.