QUANTUM-WELL EXCITONIC POLARITONS - COUPLING OF QUANTUM-WELL EXCITONSTO ELECTROMAGNETIC WAVE-GUIDE MODES

The calculated dispersion curves of excitonic polaritons in GaAs quant um wells provide up to now not even a qualitative explanation for the time-of-flight experiments by Ogawa et al. [Phys. Rev. Lett. 64, 796 ( 1990)] which clearly show the existence of a mode with photon-like dis persion above the excitonic resonance. We show that this discrepancy c an be removed by realizing that the QW constitutes a dielectric wavegu ide. The solution of the coupled system consisting of the exciton and the electromagnetic waveguide eigenmodes yields a drastically modified dispersion for the T and Z polariton as compared to previous calculat ions.