  This is the second part in a series of two papers that concern with the
quantitative analysis of the electromagnetic field enhancement and anomalous
diffraction by a periodic array of subwavelength slits. In this part, we
explore the scattering problem in the homogenization regimes, where the size of
the period is much smaller than the incident wavelength. In particular, two
homogenization regimes are investigated, where the size of the pattered slits
has the same order as the size of the period in the first configuration, and
the size of the slit is much smaller than the size of the period in the second
configuration. By presenting rigorous asymptotic analysis, we demonstrate that
surface plasmonic effect mimicking that of plasmonic metals occurs in the first
homogenization regime. The corresponding dispersion curve lies below the light
line and the associated eigenmodes are surface bound sates. In addition, for
the incident plane wave, we discover and justify a novel phenomenon of total
transmission which occurs either at certain frequencies for all incident
angles, or at a special incident angle but for all frequencies. For the second
homogenization regime, the non-resonant field enhancement is investigated, and
it is shown that the fast transition of the magnetic field in the slit induces
strong electric field enhancement. Moreover, the enhancement becomes stronger
when the coupling of the slits is weaker.
