Effect of lateral periodicity on the optical response of a QW in a DBR cavity: a simplified description via the Green function of cavity-polariton

n order to examine the previous proposal by two of the authors [ A. D'Andrea and L. Pilozzi Phys. Status. Solidi A 164 77 (1997) L. Pilozzi and A. D'Andrea Phys. Rev. B 61 4771 (2000) Microelectron. Eng. 51/52 211 (2000)] to enhance the Rabi splitting of a distributed Bragg reflector cavity polariton via introducing a lateral grating in the cavity layer, the dispersion curves of cavity polaritons (including the leaky modes of the cavity) with the diffraction effect due to the lateral grating, have been calculated by using the Green function of a cavity polariton. The analytic form of the Green function, arising from the separability of exciton polarizability, plays an essential role to simplify the calculation of complicated dispersion curves. The comparison of the calculated dispersion curves and reflectivity spectra justifies the interpretation of the enhanced Rabi splitting as due to the coupling of a quantum well exciton and a mode originating from the mixture of a cavity mode and diffracted grating modes, with more weight on the latter. This establishes a different way of enhancing radiation-matter coupling by the use of Bragg diffracted beams.