Response of exciton polariton spectra and electric fields to different additional boundary conditions

The effects of three additional boundary conditions (ABC) on the reflection and transmission spectra for exciton polaritons propagating in spatially dispersive media are studied for both p and s configurations. An investigation of the ratios of the electric field amplitudes associated with the normal modes in these media is carried out. There is qualitative agreement among the predictions of the different ABC, but there are significant quantitative differences, especially in the longitudinal polariton spike excited only in the p geometry. Contact with formulations not using the ABC approach is made. The results are illustrated by parameters modelling the 1s exciton of PbI2.