Thank you for the reply. However, this is not clear to me. My monitor does not overlap with any area that uses the periodicity feature. The only areas that uses the periodicity feature are the one embedded in the blue rectangles. This area should be substituted by a transfer matrix that descirbes inputs and output amplitudes and phases. So the knowledge of the field distribution in the yellow area (without periodicity) should only depend on the amplitudes and phases of the fields that are entering this area which are fully described by the transfer matrices, and not by the spatial distribution of the field in the blue regions (with periodicity).
Isnt that the case?