Interference of the Exciton-Polariton Waves in GaAs Thin Layers

Abstract

A large number of optical oscillations have been observed in the reflectance spectrum of GaAs thin layers grown by molecular beam epitaxy near the exciton energy. They are due to the interference of the exciton-polariton waves and allow a direct measurement of the polariton dispersion curves. The results are analysed in terms of the exciton-polariton theory taking into account the valence band degeneracy and mixing of excitons at k ≠ 0. Good quantitative agreement on the dispersion law is obtained.