  Optical fields in metamaterial nanostructures can be separated into bright
modes, whose dispersion is typically described by effective medium parameters,
and dark fluctuating fields. Such combination of propagating and evanescent
modes poses a serious numerical complication due to poorly conditioned systems
of equations for the amplitudes of the modes. We propose a numerical scheme
based on a transfer matrix approach, which resolves this issue for a parallel
plate metal-dielectric metamaterial, and demonstrate its effectiveness.
