Properties of Exciton Polaritons Studied in a One‐Dimensional Model

Exciton polaritons are traditionally considered as composite particles formed from bare excitons and photons. In a recently developed alternative approach one starts from polariton theory in configuration space and finds excitons as resonances in the polariton system. The relation between the two methods is explored in the present paper. Using a simplified one‐dimensional model the configuration space system is solved exactly for bulk and halfspace geometry, partly by numerical methods. The solutions are in good agreement with experimental reflection spectra. In order to rederive the results of traditional theory one has to apply aproximations: The “rigid‐exciton approximation” for bulk solutions and the adiabatic approximation for halfspace geometry. The influence of these approximations is discussed.