  Light transmission through bilayered thin metal films perforated with
subwavelength hole arrays are numerically studied based on a full-vector
finite-difference time-domain approach. A variety of transmission peaks
originating from different physical mechanisms are observed. In addition to the
direct tunnelling and Fabry-P\`{e}rot resonances, generally possessed by
idealized bilayered dielectric slabs, the near-field localized plasmon
polaritons also play important roles. They not only influence the direct
tunnelling in a destructive or constructive way, the interactions between these
localized plasmon polaritons on different metal films also result in additional
channels which transfer optical energy effectively.
